The Pheonix Girl, Seandre, Shekka, I'm pretty sure Anno is getting a dick sometime soon, not sure if the Tanuki girl counts. It's not as common as I thought now that I think about it unless I'm missing some characters, but I don't think that defeats my main point. If the option is offered to dedick a character I don't think that's bad. Unless it's a case like Brienne, where the result ends up overshadowing their cock-fitted counterpart. But the issue with Brienne isn't really the dedicking, it's that she is just an entirely separate character to Brint. For a futa character you just need to edit the previous scenes and add new ones.
I'm not saying EVERY futa character should have the option to be dedicked, but if it is offered I don't see how that's a bad thing, assuming the writer is willing to shoulder the extra work.