It's not an advantage.
Does it say "hey, buy these charms and you also get an extra 3 Mogu charms"? No it doesn't. At the end of the week, both players have to accumulate 50 charms, how they go about it is up to them. If Bob wants to buy them, let him buy them, if Joe would rather play for them let him play for them. It makes no difference to how the game currently is, Joe has always played for them and will continue to do so. Bob buys his but he loses all 3 bonus rolls, what a shame, oh well it's NOT LIKE IT MATTERS. I highly doubt that extra bit of loot would score him a realm first Garrosh kill and Gladiator for the season
An actual advantage would be selling Mogu chains directly up to the 10 cap, which they aren't doing purposely because their intention is not to turn the store into play to win. The experience boost, I'm sorry, it is not an advantage at all, you blink and level up these days.
The poster I "insulted" is spewing all sorts of assumptions that this is the beginning of the end and we'll be getting gear in the store. This is based on other F2P games, but news alert, WoW isn't F2P so they are testing out adding micro transactions for convenience not for "win" that can co-exist with subscriptions.
Clearly the argument is won, but for some reason certain players enjoy bitching about things that "may" happen.