I can lease 10 racks, put T1600s in two of them, and leave the other 8 empty; but that hasn't helped either me the customer or the exchange point provider; they've had to burn more real estate for empty racks that can never be filled

Seems fine to me, you used your power in two racks, to get more power will cost the provider more so you will have to pay more. This is just an extreme example of blade servers causing half a rack to be empty the facts haven't changed no matter how bad seeing empty racks feels Waste implies you could use it for no additional cost, old pricing models were vulnerable to gaming on combinations they'd not thought through. It might be easier for people to understand in these cases if the provider put yellow/black stripe tape over the unused space with a big sign saying "not yours"

I'm paying for floor space in my cage that I'm probably going to end up using for storage rather than just have it go to waste

That's nice, I hate cages where you have no room for tools or to work and the kit hits the walls when you try and unrack it. I've no idea how they fit a normal engineer in some

and we still have the problem of two very hot spots that need relatively 'point' cooling solutions.

Accepted, big fan on the back of the rack? Plenty of empty space for such solutions. High density servers seem to be vendor driven, they can charge more and make you buy the switch and other ancillaries you'd likely choose cheaper from others. And when new models come out the whole lot gets replaced rather than just the odd few U of servers. The convenience may be worth the high price for some situations Density is just another DC design parameter to be optimised for profit brandon -- You know a nanog thread has gone on too long when I overcome inertia and post. More science please.