I recently saw this on an article on ZAM and since all feedback threads are being locked I'll post it here.
Cardinal Sin #1: Double Dipping
you can't have your cake and eat it too, you can't have a f2p model with a cash shop.
The problem is that most MMOs with cash shops also keep their subscriptions optional. WoW’s is mandatory. While the pet store was on the website, it was separate and ignorable. Now that it’s in-game, the simple presence of its button induces a subtle pressure to pay more. Having a bigger wallets has made an impact in WoW (see Collector’s Editions, TCG items, and Blizzcon schwag) but the impression was passing.
That's not the case anymore. Every gameplay session is underlined by that ignorable, but irritating, little button. Players resent feeling nickel and dimed and when WoW, the most successful MMORPG in history, does it, they have a right to be irked.
Cardinal Sin #2: Ignoring the Original Problem
Selling experience potions is a problem and a big one. The simple fact is, after a certain point— say, an alt or two—players become tired of leveling through the same content. It doesn’t matter how good the quests are, after you’ve seen them a couple of times, they're played out. Blizzard's answer to this has been heirloom items and experience boosts. The Enduring Elixir of Wisdom piggy-backs on that concept but for real money.
There is a fundamental problem with Warcraft selling experience potions for cash: they're charging money to avoid designing a solution to the core problem. The vertical, Just Add Levels™, expansion scheme guaranteed that players would eventually want a way to bypass grinding the same content. Suggesting “maybe they'll pay their way out of it” isn't an acceptable solution, not when we're already paying a team of designers to actually design.
The current potion is limited to Mists of Pandaria content. That doesn't matter and players justifying it fail to see the pet store for the testing bed it is. Blizzard has discussed the problem of previous expansion leveling for years. With flagging subscription numbers, how long will it be before a 1-85 potion makes an appearance? If these sell, there will be zero motivation for Blizzard to do anything other.
Cardinal Sin #3: Making it Feel Mandatory
And simply because the above is true, buying experience potions is likely to feel mandatory. Raid groups will need their alternates, friends will want you to join them, and frankly, the phrase “the real game begins at level cap” is no truer than in World of Warcraft. There is powerful social and mechanical pressure pay up on that final level climb. Pandaria is a hike. Leveling at the normal rate for second time can feel so grindy that it’s groan inducing, especially riding on the back of the previous 85 levels.
While everything in the Pet Store is optional, given a little pressure and the general feeling that you just want to be through, you come up with a recipe for begrudged purchases and a more than $14.99/month investment.
Cardinal Sin #4: Designing for the Cash Shop
Blizzard is the king at ignoring fundamental lessons of the last few years, so it’s no surprise that it missed the one on not weighting design toward the cash shop. Selling vanity gear is no big deal when those items can be acquired in-game, but that’s not the case here. In the near future, Blizzard will be selling unique, ethereal headwear for real cash. In fact, these items are right up there with the best raid gear ever released, minus the stats. In the official post, Bashiok calls these “transmogrifiables.” That’s a category and we can expect more of it. Imagine a world where raiding no longer offered the exclusive take on the flashiest gear. That’s a real possibility. Now imagine how raiders, arguably some of the most dedicated World of Warcraft players, will react. And Blizzard doesn’t see this as a problem?
Let's also talk about pricing for a minute. Each of these head items will cost fifteen dollars. Fifteen dollars. That's beyond any form of micro-transaction and borders on price gouging. Then again, this is the company that introduced the world to the $25 sparkle pony, so it's not exactly a surprise. Just like then, Blizzard is setting an exorbitant price because they can count on players keeping up with the Joneses. More troubling, however, is a fact recently pointed out by Rob Roberts on the Horde House podcast: instead of incentivizing players returning to old content - perhaps the content these helms are themed after? - and offering players more value for their existing subscription, Blizzard is more concerned with opening your wallet for a separate fifteen-dollar charge. We can rightly ask: what are the developers more focused on, stocking the cash shop or making a better game?
There are also unique items, similar to those available in the trading card game, but nothing exists that would convince old players to return. Rather, it suggests that if you don't like it, don't buy it. Fair enough, but making an example of wringing existing players doesn't exactly make me want to re-subscribe.
Creating the perception that the design motivations are shifting away from the game and into the cash shop is a big cardinal sin.
Here's a link to the original article