Back in the early 90's I remember hearing "Smells Like Teen Spirit" by Nirvana for the first time. It was on an alternative rock station in New Jersey. I liked the song enough to buy it. I figured there was no way this band was going to be terribly big, but they'd be some indy darlings for a while. Play some theater-sized venues if they're lucky. That sort of thing.
OK, so I was way wrong about that. They became HUGE.
And they had a specific shtick. That pianissimo verse to the fff chorus. It's a good shtick. And it seemed that it was a riding trend of some indy bands. In fact, without offering any examples I will say that the quiet verse with the loud rockin' chorus was an indy trope at the time.
Nowadays there seems to be this nice trick of stompy 1/4-note rhythms. The Franz Ferdinand example is pretty obvious, but the Arcade Fire takes a while to develop into it. The other interesting thing (for rock 'n roll especially) is that there are actually ritardandos built into the songs.
Both the stompy "four on the floor" rhythm and the ritards are actually really nice tricks to have in your pop song toolbox. Those are the kinds of tricks which might actually frighten Top 40 radio programmers. At least those used to the Katy Perry-type acts.
So there might actually be a difference between so-called "Alternative" and "Mainstream" acts. Alternative allows for changes in dynamics and tempo.
That doesn't sound like that big of a difference.
And besides Arcade Fire and Franz Ferdinand are both pretty big acts. So aren't they "mainstream" now?
One thing that Tyrannosaurus Mouse can do is play dynamically. I'm not going to take too much credit for it but a lot of a rock band playing with dynamics is the result of the damn guitar player not playing too loud all the time. Because guitar players tend to do that. But if the guitar can just quiet down (or better yet, shut the hell up) the bass player and drummer can do their jobs and make things louder or quieter as their will dictates.