I would guess the Aggressor has to be one of the more expensive liveaboards, since they're selling an internationally known brand name. I'm not so sure what one gets for that brand name over other options, though. Are they really more highly insured, more safety-conscious, etc.? Maybe, maybe not.
Anyway, it sounds like competition and package dive tourism--and the attendant crowding at the dive sites--is a major factor along with fuel costs, insurance, etc., in the relatively economical prices compared with Caribbean and Indo-Pacific liveaboards.
As my only taste of the Red Sea has been a little shore diving from Dahab as a backpacker, a Red Sea liveaboard is firmly on my bucket list. I'm considering the low season to minimize crowds. Drysuit would be just fine with me, so long as the air temperature is nice. I hate crowds.
And Hintermann is indeed an inspiration.