You don't consider "Bad Romance" as "iTunes-friendly" as PF & JD? That song is extremely catchy and for some reason, "Just Dance" doesn't have a strong hook, IMO. But of course that is a moot point since BR didn't perform as well as those songs.
Bad Romance was released over a year after Poker Face and Just Dance, so it's not necessarily that it was that much less successful. That being said, Poker Face and Just Dance seem to appeal to a wider audience and in my opinion, more immediately catchy upon first listen.
I just saw the airplay gap between S&M and ET is only 30M and getting smaller and smaller
...in other words, S&M will be blocked as soon as ET video is premiering, I'm quite sure... hope it can get that #2 though and i think it will