All in all, do not demonize asking for guard. Half the time someone asking for guard might be a douche, half the time it might be someone saving you from a wipe or just a good guy wanting to make things smooth. I have more tanks in ignore than any other class. .
At first I was sort of miffed by your rant, but then became amused. You realize we are talking about the flip side of the same issue? I was laughing at the way many DPS ask for guard without any checking of who else is in the raid and are they really the one who needs it most. You are talking about lazy tanks that just throw guard on whoever for no good reason and without inspecting. Just had this in Xenoanalyst II fight on HM 16 man. Tank put guard on marauder with most HP. On inspection, 2 snipers and another marauder were far more a threat due to good optimization and higher damage. Deciding who to guard involves some understanding of how all the classes work and that is something that takes time to learn.
Lazy and poor playing abound, its is just most apparent when the tank is guilty and most common (maybe just by sheer numbers) in DPS.