I'm suprised that more people don't really seem to say this. You put a bodybuilder on his own on a (massive) stage and you're asking for trouble. Most bands cannot really generate enough energy to sustain a huge stage or large venue - especially one that is half, quarter filled .
It is horrendous when you combine that with poor production values and guys who are just not configured to be stars. Fact of the matter is, the smaller the venue the easier it is to generate and maintain energy. These promoters who insist on going into oversized venues with overpriced tickets (to cover the fact they will not come close to filling it) have it all wrong. Anybody who goes to sporting events around the world will understand that more people crammed into a smaller space makes for a much more uniform vibe.
Rant over.