I'm hardly what most environmentalists would call an "environmentalist", but one cost here is the increase in carbon footprint. Of course, to the company the cost/benefit analysis errs on the side of just spinning up more boxes. But from a larger perspective, taking some extra time to make more efficient use of machines could have a drastic impact. Many optimizations don't require months to implement. Many of those are even avoidable with a bit of foresight.