If you are low on chips, you can't play properly post-flop. The best move is a pre-flop all-in with your strong hands.
All-in with a big stack pre-flop could be a good move too. You can do that when you don't have a great hand, but you expect everyone to fold (blinds+antes stealing). This is a rather bad move when there are other big stacks left to act, though. If you have a great pre-flop hand, the big stack all-in could be a valid move when there are hero bluff-catchers around.
In the beginning of tournaments, when the blinds are very small, the pre-flop all-in tends to be a big waste, unless there are many chips in the pot due to high betting activity.
This idea can be useful in a tournament. For example, when the first time you bet pre-flop all-in with aces, and then aces come again, you bet pre-flop all-in again, then the second time your opponents can answer the allin.
Short Stack, yes I often would go all in with AA, but obviously not just with aces. With deep stacks, no I don't go all in with AA much as it is pretty transparent that you probably have a very good hand.
Any move should have +equity, going all in on the preflop means either a desire to double, or a desire to win the blinds, good or bad depends only on the goal you are pursuing and whether you managed to realize it.