I wear foundation everyday, and have a huge collection - Studio Fix, Aromaleigh Glissade and Voile, some TMs, LM Oil Free, Kevyn Aucoin SSE, CoverFx, Revlon cream-powder compact (forget what it's called), Maven Liquid Mineral, UD, PX, oh, gosh, the list goes on and on.
I suppose my skin is ok, but I'm pale, redheaded, freckled. I look ok without makeup, but my features just sort of disappear. So mascara is a must, and eyebrows. And by the time I've got those on, bare skin looks a little unpolished to me, so I do foundation. Many formulas contain beneficial ingredients, like sunscreens, moisturizers, soothers, retinoids, antioxidants, so they can do double duty and help nourish your skin as well as smooth it out optically.
But I'm a firm believer that a girl should only use that which makes her feel happy - if you love it, put it on, if not, forget it. You are beautiful without a speck of makeup on - everyone is. And cosmetics are an extra - if it's not fun, or if it doesn't agree with your skin, then skip it.
(Blasphemy, you say? Not really - I'm 40 this year, and just totally into doing whatever I want, from no makeup one day to full on showgirl/Moulin Rouge makeup complete with false lashes the next. I do it for me, not for anyone else. I think all of us should do this for ourselves, too, rather than to conform, or to desperately gain approval. Note - getting a few appreciative looks and loving it is NOT the same as a desperate need for approval. So just enjoy what you use, and bag the rest.)
-b.