One day maybe you'll try to win a warfighting suicidal game, maybe one of the tournament scenarios where the player finds himself in a difficult starting position. Then, you might find it necessary to refer to such strategies in order to survive.
This is actually why I won't play on Suicidal; I don't like the fact that it's necessary to engage in "gamey" strategies in order to compete with the AI. I'm certainly not trying to complain about anyone else's playstyle, but speaking solely for myself, if I ever reach the point that it's either Suicidal or a walkover, I'll probably just abandon the game for a while.
I will note that in my current game on Tough, it has been possible to sustain overall approval in the 70s with a tax rate of 79%. I do have two fully maximized morale resources. Income is about 200 bcs/turn factoring in huge leases from a fleet-wide upgrade and an enormous espionage budget that I don't actually need, but am operating with now as I'm at peace with everyone. So good approval and (by my standards) a strong economy aren't incompatible.