Firstly, I don't know how you're assuming the microtransactions will kill the game's balance the instant you read they exist. What I'm saying is - don't judge a book by its' cover. The influence points, like Akyko said, will only help you in ways that won't tip the scales between you and other players. Like in many other games, its' designed for those who might not have as much time to play the game, and it'll work just fine.
How do we know this? Well if you haven't noticed, a lot of games have been going free to play, including some big titles like Lord of the Rings Online. It has been proven that F2P brings significantly more profit to the developers than a subscription model.
Of course LOTRO had to go through some significant changes which might not have favored some people, in the end they gained players and those who continued to pay a monthly fee received a lot of their previously acclaimed bonuses.
Likewise in DoF - everyone plays equally, and the shop stuff just helps boost you a little bit if you've not had time to play or want to catch up to your friends etc. LOTRO is probably not the greatest example though as there is quite a gap between base free players and those who pay the full price; DoF is unlikely to have anything even close to that.
So, in short, it won't be as damaging as you assume - and it is definitely the best way to go as proven by recent trends in the gaming industry.