Few (non-definitive list) reasons to have as large a stack as you can:
1. If you get a monster hand, you'd prefer having as large a stack as possible. If you flopped quads and hadn't topped off, so you only had 50bb's in front of you, you'd be a little disappointed in the results.
2. There are plays you can make deeper stacked that will not work w smaller stacks. If effective stacks get too small relative to the pot, you have to have a hand in order to make a bet/raise.
3. The shorter the effective stacks, the fewer streets of play. If effective stacks are 50bb's, we're not going to worry about playing the river much in an aggressive spot, since all the money will be in on the turn.