This is an odd theme, to be sure. We take common words (well, sometimes common, sometimes not, as I'll discuss below) where the second part of the word can be reinterpreted as a verb, and then make them contractions with "not" to amusing ends. I liked it very much when I first came across CATSCANT (23A: Jazz players are incapable). I liked it less with BUSHWASNT (35A: W. never existed). I mean, "bushwa"? Is that the underlying word? Apparently it means nonsense, which is what happened here. Where did the S in the final answer come from?
KATYDIDNT (55A: Singer Perry opted out) is straightforward and acceptable. ANIMUSTNT (18A: Singer DiFranco should heed a warning) comes close to working. But the T is again added in, and the word "animus" does not sound like "Ani must" because of that missing T. And then we get MATHISNT (49A: Calculus disappears). "Mathis"?! This is not a common word. It is a name (Johnny Mathis springs to mind), but then it's the only name used in the set of theme answers. I'm going to cry foul. I will say I liked the clues a lot, but I'm not sure why they're in italics.
I have to say that I thought I was going to love the puzzle from the NW section. OBAMA crossed with BIGEARS is great. I like ADOPTED and any reference to MARISA Tomei is a winner in my book. And there's lots of great stuff in the rest of the grid as well. SASHIMI next to TINYTIM. TOTEBAG and VANGOGH. I like PEERAGE, and OCTET above LOWNOTE is fun.
I didn't like the middle section, with OASES and OESTE right near each other, but they support CROUTON and KENNETH, so I can't complain too much. I've never heard of a SKIBOB, but it looks like a ton of fun.
There's some crosswordese scattered around, but I won't complain too much about it. Overall, the fill made up for the strangeness of the theme, and I guess that's what Wednesday is all about.