Got early access to it as well (not validated yet, Stripe's interface is really not user-friendly and asks for papers I don't usually have handy).
And yeah, I totally agree with you. I felt really weird writing the tiers. GitHub's wording seems like there shouldn't be any reward, so I didn't put any reward (and I don't really feel like pushing rewards anyway). But why do tiers then?
Perhaps it will help herding people into making it to higher tiers? I don't know, from my point of view, I'd prefer let people free.
As for person vs project, I don't really have the problem, though I agree with you. I feel like small projects won't setup this, because it feels much more complicated than doing a paypal (perhaps paypal got so cumbersome as well? it wasn't when i made an account there.), and big projects will need teams.
I have to mention that I also have an account at liberapay for donations, and they do handle teams! (they basically do a round-robin, so you need enough donaters)
Edit: Yup, Stripe is really annoying. They somehow denied my ID, without saying why, and I can't seem to link this account into liberapay.