Maybe, but that won't resolve the issues. The same problems arise in 25 that arise in 10 and that's why we're here. Depending on your heal comp in 10 you can get wildly different results but in general the same concerns. In 25s you have more flexibility in regards to your healers but its still very much smart heals and AE spam fest.
The issue doesn't arise from raid size, but is rather a result of balancing to cater to both sizes. Regardless, we still come to the same outcome: healing is not in the hands of healers any longer. Sure we can hit Wild Growth, Prayer of Mending, Chain Heal, Healing Tide Totem, Wild Mushrooms, etc., but once we hit it, that's it. It chooses the targets for you, it heals them and you can do it again. That isn't interactive enough, nor is it interesting and compelling gameplay.
OTOH, neither is single target spamming of yesteryear.
In my mind, a compelling style of healing would be something like a cross between renewing mists and rejuv. A spell that jumps to the targets, but you chose the targets. In our current healing environment, that could never work. It would require the loss of 3 GCDs and in a world of constant and predictable damage, that's a lot to ask. However, the idea itself, has room to grow. Imagine if the initial cost of RM was high, but the subsequent 2 casts, cost no mana. It would be working as it does now, but with more player interaction.
Now, don't get me wrong here, I believe that smart heals have a time and a place. I just don't believe that time and place is every available CD. As it stands right now, smart heals are taking complete control of my healing. Plus, with the proper planning my RM can be on every raid member. I could achieve the same result if RM cost 3 times more and jumped to every player with a 24 second cd.
I think a secondary power meter akin to holy power, eclipse, or even a combo system could have some interesting gameplay elements if properly designed, but as we see with Holy Power, it can also lead to non interesting gameplay because there's no choice. The mechanics have moved us away from interesting choices, clever gameplay and encouraging creativity, to spam X spell @ Y. Spam Z spell on CD. Boring, unintuitive, uninteresting and non interactive.
Mastery is also not as interesting as we were promised, you either take it or you don't. Your class is typically balanced around that. For monks, we don't take mastery in general because it is a non interactive, uncontrollable, uninteresting spell that relies 100% on other people to be worthwhile. For druids, its go mastery or go home. It is just so powerful, not playing in that playstyle is a hindrance to your raid.
IMO, mastery should create an alternate playstyle that is very strong, but comes at the cost of things like crit and haste. Perhaps if your spec prefers crit, then mastery could benefit from haste. Or make all three so amazing that having to choose between them is a tough decision. You could go full crit or mastery or haste or spirit but it would come at the cost of something. Or you could stack mastery and crit and have one playstyle, but if you stack mastery and haste you get a completely different playstyle. Or you could stack mastery and spirit or spirit and crit, so on and so forth. Choosing all of them would be a weak option.
Everything is pretty cut and dry when it involves your spec. I choose crit and haste over spirit and mastery as it is. My druid chooses Mastery over everything else. One priest uses haste and the other doesn't use it as much. They're already predetermined and experimenting with other choices usually only comes after a big change to that specific class mechanics. This is an area I think they could really explore and open up some more interesting options for gameplay.