NFC payment isn't revolutionary, but it's definitely added convenience.
For one thing, I don't know about you, but my cellphone is frequently right in my hand whereas my wallet is not. Particularly if I've been waiting in line at a store, my phone is almost guaranteed to be out as I read the news, play a game, read a book, etc. to pass the time. It's just another step to put the phone back into my pocket, pull out my wallet, pull out the particular credit card I want to use.
Second, with respect to taxi cabs (which are a way of life here in NYC), one almost inevitably has their phone out, and having to do the phone/wallet juggle at the end of your ride is a surefire way of leaving one of the two behind (as many, many, many New Yorkers can attest to).
Finally, there are times when (like on a run) you may have your phone with you for music, GPS tracking, etc., and it would be nice to leave your wallet and money at home, knowing you could buy some essentials at the store if you needed water, food, etc.
When (if?) mass transit systems adopt NFC payments, it will be another bit of convenience, because there are constant jam ups at the subway turnstiles as people fish around for their MetroCards -- don't understate the amount of time it takes to pull a card out of your purse, especially when a line is building up behind you and the train that everyone wants to get on just pulled up to the platform.
It's a step in the right direction.