I've always like Fletcher, and he's certainly a great player to have at United.
Sure, hes not good enough to be a regular starter. But he's here, works hard and is willing to wait for his chance which is great. You can't have a team full of Rooneys, Ronaldos, Berbatovs etc, so the Fletchers, Parks and O'Sheas are vital players to have at United, not only for on the pitch, but also off the pitch as they certainly add to the team spirit and the reputation of United in the way they behave and the way they represent the club off the pitch.
He's been on good form this season, and has scored 2 vital goals already this season (3 altogether?) He is still a United player, so should be supported (as some of the same supporters say about Ronaldo.) He may well move clubs when he gets older, but while he's here he should be appreciated and we should be glad to have him.