Good points Havish, in fact VCU has contributed very much to this reversal - I think the crowd stays captivated with VCU's dances because of "gimmicks" like the low-spin move where everyone holds a daang in one hand while nearly sitting on the ground (silhouette of this move is your logo - kind of a signature thing I guess). It is not a gimmick per se but everyone goes nuts when you guys do it because you set the music to it properly and all the dancers get into it.
So, to come back to the topic, crowd attraction is based on
1) Variation (ie going really fast and then slowing it down for (as an example) a VCU spin move, or going crazy with daangs and then everyone freezing to stand in place, arms outstretched, heads facing the sky, and shoulder shrug a la Nachdi Jawani). Or like when SGPD freezes while the Jump Around track comes on and then starts swaying and pumping up the crowd - this variation in beat, the dramatic pauses, keep people interested. A dance which is entirely fast is not enough usually, or even 1 jhummar segment interspersed is not enough, you have to catch the audience off guard and change things up (this is why Columbia's Pause-Rewind-Wind up the guy who stopped dancing - Resume Dancing gimmick works, and why KJ's "freeze-part the dancers like a curtain to reveal 2 little kids" works - if the two kids just ran onto the stage it wouldn't be as surprising, so not as effective,,,,notice how the inclusion of Jasmine in LBC's dance cannot itself be called a gimmick - the fact that she's hidden from view and brought in as a surprise makes it more of an eye-catcher.
2) Crowds want BASS. Can't deny it, gotta love it. As people said above, all this really means is sick music. If Jaan Punjabi or Sher Punjabi are playing, cmon, how can you sit there and NOT be excited (unless, of course, it's the 9th time you're hearing those songs *ahem* every competition this year *ahem* but you catch my drift)...
3) Energy. Gee, Arjun, really? Yeah, goes without saying. If you're dancers look tired and then suddenly do some crazy dragon/peacock/phoenix stunt, whatever you want to call it, you're not gonna get the same level of cheering as you would if you're engaging the audience all along with facial expressions. Ok over and out.