You people do know that an album is better served by singles that have memorable melodies, correct? In no way should Mofo have ever been released in that regard, unless it was just for DJs.
I'd also say the same thing about Gone, which while extremely powerful in the course of the album, is not exactly what I would call catchy.
Last Night On Earth, has a decent melody in the verses (especially in the second part, which could be considered the bridge), but it has a loud, shout-out chorus that would have sounded great had it received airplay. It's not the strongest song on the album but the idea is to get the attention of the listeners without driving them away, which Discotheque did to an extent, and which Mofo would have done even more.