Sorry, no I'm not. The idea of 'fun' is currently being derived from what The Avengers was during it's run. And that's not Batman.
ALL comic books and graphic novels are fun. If they weren't, then why would we be fans of them? However, Batman is not a colorful character (per se) -- nor is The Punisher. So I'm not against a 'fun' Batman at all. After all, I adored the B:TAS and the Arkham games, but it varies to what level of 'fun' is suggested here.
You're wrong though

. Your merely pointing out that Bruce Wayne is a sociopath with zero sense of humor, agreed (kind of, he's been 'lighter' or 'darker' depending on the writer, but basically a not happy dude). Alfred Pennyworth - dry sense of humor, good for one liners. Robin (pivotal character), Nightwing are both humorous, good banter. Could see a very Downey Jr. take on Dick Grayson as Nightwing for example. Have him being very quick witted, and very cheaky with the ladies. All that is very consistent with the comics. Joker, again, can be very humorous on top of being murderous, and fits with multiple takes on Batman. Then you really have a colorful cast of villains over all.
No Batman could have the 'tone' of Avengers. Batman simply wouldn't be the one responsible for that kind of dialogue, but you could certain have a comic bookish Batman take, and it's fits seemlessly with the comics. I mean Cap wasn't really funny in Avengers, and Batman has some parallels there, he's very by his own book and no one else's, and a bit moreso than Cap.
Remember, even 'Night of Owls', a very current Batman story that honestly has movie potential has a complete fun element to it. Owl ninjas? It's great, btw.
So I just completely disagree. There is too much Batman canon to consider to say that Brad Bird can't capture some of it, or that the style of Avengers is inappropriate. It's completely appropriate for Batman stories like
Hush, Under the Red Hood, No Man's Land, Arkham Aslyum, or villains like Clayface, Mr. Freeze, or even Ra's Al Ghul would be given good treatment. I in fact think Nolan really only did a sub par Ra's thus far, I think he dumbed down many great aspects of the character. There's a ton of high concept fantasy and sci-fi that has always found a home with Batman, and it'd be nice to see a movie that does that.
I think you also have to realize that not having to necessarily redo the origin now, which is probably the case, they can make a more expansive universe not just pigeonholed into our own.