My mind also went straight to microtransactions, so I looked it up. Found this right here on The Escapist:
http://www.escapistmagazine.com/news/view/131645-Titanfall-Wont-Have-Micro-Transactions-According-to-Respawn
So unless this and several other comments made by Respawn turn out to be totally false, I don't think we have to worry about the power-ups being Pay-2-Win. God, can you imagine? It would be a total deal breaker. EA may be that cynical, but one would hope that Respawn would understand how bad that kind of microtransaction would be for their reputation as a new developer. I wouldn't be surprised to learn that EA had tried push such transactions on Respawn, but when your founders are the creators of the most lucrative videogame IP of all time (CoD), you probably have more leverage than a smaller dev.
Now here's hoping Titanfall and their new MS Azure cloud servers actually work on launch day.