I think I'm just playing a broken record here, but most of my issues with the fandom tend to stem from the 18+ category of work. Seriously, it gives the fandom a bad rep, and you're only solidifying the stereotype that furries are perverts, when you decide to draw/write nothing but porn, especially the outlandish, weird, and sometimes vile kind that somehow makes it past the no-porn rules on some sites (I'm looking at you, deviantART!).
My second gripe is more or less a shallow one. And that is the lack of diversity in fursona species. Seriously, there are TONS of animals out in the world, a lot of them more exciting and more unique than the fandom favorites. All you have to do is a little digging and you're bound to find something that strikes your fancy.