In regards to everyone talking about "grinding", I don't see how that really applies here. The way I see it, grinding is when you have to do the same thing over and over in order to eventually be able to progress with the game, e.g. in MMOs when you have to kill 140,000 goblins to get enough XP to progress to the next zone or whatever.
But here that doesn't apply. Here, you play because of the playing itself, not to progress. Like in the ME3 multiplayer, I played that hours upon hours not because I "needed" to unlock all the unlockables, I played it because it was fun playing it. The unlockable content is just something extra, something that gives the gameplay a bit more variety, it's not something you need to play the game. Sure, there might be that one special weapon or character you really want, but if the MP has no value for you unless you get that one specific character, I don't see how it can have much value even when you get it.
Sure, go ahead and decry the presence of microtransaction on the grounds that it will add so much grinding to the game. But then also go and complain about the grinding in every MP game ever, because they all work the same - you do the same thing over and over again. Not because you need to, but because you think it's fun.
Personally, I'm not going to spend a single actual coin in the store, just enjoy all the extra free content I get thanks to those who do.