Hopefully you will all have fun meeting singles and try out this online dating thing...
My profile has been to this point has been vague about what i want and who i am, but before I re-write it with a fresh outlook, I just want to get a general idea if this is something I should include. Also, before anyone comments about there being more to a person than breasts, I already know this. That is not in my profile and I don't ask for pictures lol.
So no, I don't think it would be overly rude, but watch it, it's not something you should put in a profile IMHO, better save it for a more personal context where it can at least be approached with some humor and some semblance of good timing. That person wasted both your time by not being upfront about what she wanted in the first place.
I think you are putting far too much weight on breasts for your future happiness lol. Don't give me physical attracted junk, if she is for you then you will love touching her and looking at her regardless. Had it been right in the profile then no contact would have been made in the first place. A lot of large-chested women (from what I hear) have been objectified for their breasts since early teenage years, and hate it.
I do however look the person in the eyes while talking directly with them, as I would for anyone you talk with. It's not wrong to ask - but it will severely limit the pool of people that will interact with you.
Still, if that's what you're here for, that one thing and one thing only, then you might as well eliminate the rest.