Panzertorte, it largely depends on what area of psychology you are looking into (social, I gather from your profile) and which schools you would be looking at for a more prestigious PhD - for instance, do these top tier schools seem to want a MA before a PhD? Would having an MA bolster your credentials, meaning might you be able to get a publication out the NYU MA program? (Talk to current students to discern this, or even a particular professor you'd be interested in working with there in the future.)
Also, you have to keep in mind that if you're not fully amped on the PhD programs you've been accepted to, ask yourself if you can stay in those programs for 5 years? Would you be happy? Would you be getting the intellectual stimulation/publication experience/expertise you desire? Five years is a helluva lot longer than two.
Taking another two years isn't necessarily a bad idea...after all, you'll likely live well into your 80s, and I don't assume you're 78 right now. And while MA programs might seem as though they're money makers for schools, this doesn't mean you can't turn your money suck into a money-maker (or reputation maker) for yourself during your stint. And, honestly, NYU is NYU...just like Harvard is Harvard. Many people (and employers) would pay for a basket weaving degree from these institutions...
These are just some flip-sides to consider.