Well, I don't mind if the game has futa content, but I'd rather be warned in advance so I can ignore the game right away, instead of getting my hopes up that it would even remotely interest me.
There's a couple of genres that developers should warn about in advance. Futa is definitely one of those, same with Gay content, incest, NTR, vore, gore, rape, beastiality, extreme bdsm and bimbo-/sissyfication. Those are probably the genres people have the strongest diverging feelings about whether they want to follow or even support. It is rather frustrating to be several updates into a game, and a developer suddenly drops something that you have absolutely no interest in seeing, without clear indication it was heading there. These genres are still fairly general, so mentioning in advance that some type of content will be there can't really be considered a spoiler. There's no reason for a developer not to mention them in advance.