The stigma against funner stems from the idea that fun was a noun, not an adjective. But it's used as an adjective all the time now, so there's no need for the stigma. It's just one of those language bugbears that won't go away.
And by the way, cromulent comes from The Simpsons. There's some quote from Jebediah Springfield saying that a noble heart embiggens even the smallest man. Someone criticizes the word embiggen, and Mrs. Krabappel says that it's a perfectly cromulent word.
