Back to the Moon
It does make sense to use HLLVs rather than smaller ELVs (pdf file) if a manned trip to the Moon is a goal.
For instance, the CEV should have a Lunar access module docked to it on the way to the Moon (that's what saved Apollo 13's crew) and not sent separately.
And also, HLLVs could create a market for large satellites.
Raoul