alt Hacker NewsRight, but if it's noticeably hotter than the environment, then that temperature difference could be used to drive a heat engine and get some more useful work. So the knee-jerk response "omg, we see the heat from space? it's gotta be wasteful!" is kind of correct, in theory.
Some people are saying "waste heat" in the technical sense of "the heat my industrial process created and I need to get rid of" and others are saying "waste heat" as "heat humans are emitting into space without slapping at least one Carnot engine on it yet".