i wouldn't go quite as far as comparing dbsk with nsync (because dbsk is actually good) but i get where you are going with that.
and you are right about suju not having an equivalent - think about this: they have only ever held 3 full concerts, and that was all only a few months ago. any band in america (and not just pop bands, heck not even just famous bands) would try to do as many concerts as possible and tour as much as possible (i have NEVER met a band whose focus was not touring and making albums, and i have worked at numerous concert venues/toured myself/lived with bands, etc).
they are not a band just for music's sake, they are a whole entertainment package. mini concerts, live (sometimes) performances, radio shows, variety shows, mc-ing, some legitimately good singing, songwriting, a full length movie, dramas, charity events (how about the marathon they just did yesterday? did anyone see that?), commercials, etc, etc, etc.... these boys have more schedule than they can just about manage. but that is what makes them special, and that is why i like them even if their music is not amazing (sorry if anyone thinks that it is, i am not trying to disrespect them in any way, just stating my opinion).
and i just have to say this (someone said this is like AA right? haha..): the fact that they cry so often even on tv is just amazing to me. they are all such softies, i love it! that's another reason i love them so much. seriously, i could probably list 20 times i've seen eeteuk cry on tv - i'm not even sure if i've ever seen my best friend cry in real life! i'm not sure if that's a cultural thing, or if it is just them. either way, i think it's cute (: i feel much better now, after admitting that.