Well with the exception of shoving because you are low on blinds and you are into a push or fold mode, because your blinds dont allow you to play post flop.
There is also the matter of not getting enough value if you dont shove or getting donked or bluffed if your postflop play isnt good.
One example is this.
You have
and decide not to shove but slow play them. You get called and the flop comes
, now that is a scary board for your aces, opponent can have the straight or the flush already. Now how do you procceed? Shoving is out of question, if you bet and get called you will play turn and river cautiously and go for pot control. You go to showdown and your opponent show a pocket pair of 6. If you shoved preflop he would call with the worst hand and you would get all his stack, but now you won only a small pot.
Now an other example. You have aces again, and the flop is something like
. Your opponent shoves. What you do with aces on that flop? You call. If he had pocket sixes now you lose your stack. If he had 65 you probably lost again, if he is on a draw now he have more possibilities to either call and crack your aces or if lets say he had AK that he would call a preflop shove now if you bet on that flop he will fold and you will win a tiny pot again.
And now thats aces. Kings or Queens are even worse, cause any Ace on the board can kill your action. So you may end up with a little pot or lose big if you decide to slow play a big hand.
Shoving big hands is +ev, especially with all the loose players out there who are willing to call with pocket deuces or Ace high.