OP addresses a lot of what needs to be done. On the Refresh issue, perhaps there can be a button the host can press once every minute to refresh his map. So they can't spam it, and only non-AFK hosts get their lobby to the top. This can only work with unique lobbies though, naming is not necessarily needed however (though personally I would prefer it). It could possibly be an issue with advertising bots (e.g. make a map title advertising something and have an autoclicker refresh), but given the fact that SC2 lobbies automatically start when full, this might curtail this attempt. Even then that's essentially nonissue, it took forever for WC3 to get to what it is now.
• Review Downvoting. With the Review system I suggest that downvotes be possibly too. Sure, everyone would love to have a happy slappy perfect world where it wasn't necessary to dislike something, but if we want quality reviews, then you need a better filtering system. For instance, some of the top reviews on Mafia right now are outright lies. There's nothing obscene about them though, so they're not worthy of being reportable. Understandably part of this is because the Mafia community is trollish in general, but it's also because some guy got mad at DR and spammed the chat channel for weeks to get people to upvote his review. So this is an extreme outlier case. But the fact that this is possible is disconcerting. This suggestion is in Skunk's list. If Blizzard wants to keep it all go-go happy and fresh, it need not show the downvotes, all it should do is take away 1 Helpful, so it goes 2 helpfuls to 1 instead of 2 helpfuls 1 unhelpful. Then if it gets enough it just stands at 0 helpfuls and goes no lower.
• Hover Preview. Something that might also help, but would be a bigger UI change, is that when you hover over a game in the Open Games list, it brings up the map preview, i.e. the hand that Left 2 Die has, the picture that shows up on Up and Coming. At the moment, the list looks incredibly bland. It's actually even blander than WC3's was. In WC3, if you had the map downloaded, you would get the minimap preview or a custom screen they had. It adds visual flair, which makes the game feel less monotonous. Even if you didn't have it downloaded, a question mark came up, so there was at least still some art. If you had a hover preview (or something analogous) on the Open Games list, it'd give people a chance to get interested in the game, or for the author to rope people in with an interesting graphic. Either way, the list as is is incredibly dull.
• Genre Customization. Being able to set one's own genre would be nice. There's so many "Other" maps. I understand there's a sorting option, but why not have the defaults and simply have the "Other" sort option literally sort for other genre descriptions? Most maps on BNet are more than simply one genre. It's sad that a game like Island Defense has no proper classification, despite its gameplay being classic throughout custom gaming history. Is it Action? Sure. But it's also Strategy. And Survival. And even Tower Defense. So you get about half the game list being Other, which says that Blizzard either needs to add a ton more genres or it should just let mapmakers be able to customize their Genre. And really, more customization options only mean more good things. To repeat, for any unique genre names, you can still just have them be listed when one sorts by "Other".
• Better Preview/News Navigation. When I go to Overview, where mapmakers can put up to 5 preview images, I should be able to navigate to the next image by hitting my arrow key or by being able to click on the side of an image, and if I want to enlarge I just click anywhere near the middle. When I hover near the sides an arrow to go left or right respectively should appear. "Click the tiny boxes to navigate" is 90s website design, it really needs to be brought into modern times. This concept can also be applied to the news you see when you log in.
• Opting out of Website Warning. When I click to go to a mapmaker's website, the warning screen should pop up, but I should also have a box to check off that says I can choose not to see this warning again if I want to. I've obviously made the decision to go to the website. Of course, the reason Blizzard does this is a legal issue, but they would also be legally covered if we choose the option to not see that warning again. Because this box pops up every time, maybe I won't feel so inclined to visit now, which makes me less involved in that map which means that map is less likely to grow.
• Remove Empty Space. In Overview (again), those boxes have empty space below them above the Play / Create Private Game buttons. Why? Why do we have that empty space there? Let the boxes use up that space, so I can be shown more text without having to scroll.
• Open to Public.Also, this is very, very important, we need the option to Open to Public from Private Games again. This was one of the few things BNet 2.0 did right. I do not know why we went backwards on this and removed this option.
• Friends System Overhaul.Now, for the friends system. BNet 2.0 also went backwards on this, this game is very antisocial. WC3 friends were much better, for the most part. I should be able to see what games my friends are playing, at least, mutual friends. This should be even easier given the fact that lobbies have standard names in SC2, so if my friend is playing Squadron TD it'll just say he's playing SquadronTD. Call me crazy but I don't want to be throwing out my real name and email address (remember - it's a detail you use to log in to your account and Blizzard wants you to give that information out publicly in order to get a Real-ID friend). Frankly, this was just a botched attempt to be "social" and to keep up with Facebook when they didn't need to. They just moved over most of the benefits of WC3 friends to Real ID. If I have a mutual... "Battle-tag".. friend, I should be able to join his open games, see what he's playing, and so on. Part of the reason the custom scene of SC2 has fared so poorly is because the game does not lend itself to community building, it is a very antisocial game. And custom games thrive on the communities behind them. Clans in HotS will help this, but the friends system needs a major overhaul. If I'm close friends with a person, I'll tell them my name. There's no need for me to see it all the time over their username. Trust me Blizzard, I'll be able to remember it's them when I see their account name. Don't force me to give out my full name and email just so I can get a friends system that's about 70% of what WC3 was. Similarly, I do not need to have my real name show up above my friends list. I know who I am. This can be a potential problem for streamers as they will have their real name show up to possibly hundreds or thousands of people when they may not want that.
• Achievements. Add as many more achievements as possible. WoW got this right. Most achievements on SC2 are just boring grinding achievements. I had plenty of fun grinding out the unique achievements with friends. Achievements keep people playing and having fun. It would be an absolute boon if Custom Maps could use achievements that actually show up in the SC2 interface with their own graphic. They need not count to the achievement score in the top right. This will greatly promote custom game playing as people try to get specific achievements. You can let them have their own points too, it'll just be specific for that game (i.e. having 1000/1000 achievement points in Squadron TD will only show up in its own tab, it won't be added to the top right). There would be a great many ways to implement this, so it's pointless of me to try to describe how this could fit in with the current UI as there's tons of ways to do it.
• Profile Editing. Why was another feature from WC3 removed? There's empty space in the profile region. Let us write up whatever we want about ourselves. Have a Report button if you're worried people will write objectionable content.
I could go on and on about the endless quibbles or gripes I have with the SC2 UI, but this will do for now as it's already a wall of text. I don't see how any of this can be controversial, though I'm sure someone will find a way, but there's so many common sense fixes/additions that the UI could do with right now.