Here's something I've never quite figured out: why is it that Moldvay included both increased XP costs per level for his dwarf racial class and level limits? I can see it in the case of the elf, because it's effectively a multiclass fighter-magic-user, but why should it cost more XP per level to be a dwarf, when he's basically just a fighting man who can only reach 12th level? The halfling, for example, requires exactly the same XP per level as a human fighter, but a dwarf, meanwhile, requires more. As I see it, if you're already penalizing demihumans by limiting their advancement, then why penalize them a second time by requiring more XP per level because they possess a handful of racial abilities of limited utility?
(There's also the issue that there's no precedent for this approach in the LBBs but that's another matter).