Isn't basically all that you gather from facebook interests and location? That is hardly a huge barrier for a non-facebook login.
Not having your own login is lazy and shady, and having an own login is appreciated even by those that ultimately choose to use facebook.
Right now it is based on common interests and location. In the future it will likely look for other data that similar connections can be made on.
Airtime recently launched and they are following the same model as it turns out due to their close alignment with the Facebook community and the data it provides.
There are plenty of "meet new people" sites out there where you enter whatever you want about yourself. This is a different angle on that which provides functionality leveraging Facebook which Facebook itself is not going to provide.
You need a Facebook account attached to become Facebook friends.
Allow users to change email or msn over, say, the chat (as they can already). Problem solved.
Your arguments for locking yourself into facebook are artificial. Doesn't matter if you plan to incorporate other things as well, it doesn't break your site to go without the information of "likes" or whatever, especially considering that you hardly will ban facebook users that doesn't "like" anything.