Huh? This is a dice game. Nobody knows before they roll whether 2 dice are going to make or break them. All anybody knows is that more dice = better. It increases your chances of success, decrease your chances of glitch, decrease your chance of failing an opposed test and in the case of an extended test even 1 more die can add up to less time by the end (and fewer glitches). It's especially great with unopposed tests. +2 dice is more hits on matrix perception and more info when you're doing matrix search.
Even if you're rolling "enough" dice, you can still get unlucky. 2 extra dice will decrease the chance of that situation where you'll need to use edge to reroll. And IF you happen to get into cybercombat, then having 2 less dice on all your attacks and 1 less D6 init will mean that you're less likely to win.
Shadowrunners get into all kinds of fights all the time with all kinds of chances to take physical damage. This is not the boogyman, it's just another one of those times. If you know you're going to lose a fight then yeah, make sure you're cold sim, but if you plan on winning (however you define that) then you've got to maximize those chances of winning because all you ever have is a chance to do anything. VERY few things in this game are a sure thing where you can point to 2 extra dice and say they will not matter.
