SSBB is a different (sub-genre) than some of the fighting games it's being compared to. It's like comparing Mario Kart to Gran Turismo, would it make sense to have banana peels in Gran Turismo for example?  With that being said the fighting genre is indeed very stale and needs new ideas.

No; the purpose of Mario Kart is to give a fun racing experience and the purpose of GT is to give a realistic racing experience. However, the purpose of SSB and all other fighting games (no matter how realistic they look) is to give a fun fighting experience, because you cannot get realistic fightingin games in the same way you can approach with racing. Therefore SSB should be considered with all other fighting games.

Why not?

Controls. It can really feel like you are handling a car (because cars have abstract controls themselves) but real fighting is nothing like button mashing.

That really doesn't make sense.  For example the Madden games attempt to go for realism and it doesn't feel like you're really running with the ball or getting tackled.

I'm just saying that traditional fighters and SSBB are somewhat different and some things that work in SSBB may actually not work or take away from traditional fighters.  It's like pointing at the Fifa Soccer franchise and saying that Soccer is getting stale on consoles and then pointing at Mario Strikers Charged's use of items, trick shots, etc at a way to fix it.

@OP: No, not in the least, I don't compare Smash series to regular Beat 'Em Up's at all. SSBB to me is more like Worms, strange as it may sound.
To me, it seems like a comparison between TOCA and Big Red Racing, both fun games, but in two entirely different ways!
I enjoyed SSBB much more than the previous installments of the series (especially with the GC controller) but I'd never choose it before other fighting games since they give me an entirely different experience. (Why is it so hard to distinguish SSBB from Tekken or DOA? I think many take this game too seriously and I'm quite sure Nintendo never intended it to compete with these titles.)

I think that Super Smash Bros. Brawl is the greatest fighting game of all time, and makes all other fighting games obsolete.