Is there something to Critical Hits themselves I've missed?
The biggest thing is that criticals ignore defense boosts. AND they stack with STAB bonus.
Frost Breath and Storm Throw are AMAZING moves as a result, some of the most powerful in the game. Storm Throw, despite being only listed as 40 attack, after crit and stab is in fact a 120 attack move with 100% accuracy that ignores defense boosts., and Frost Breath is almost as good with 90% accuracy.
There are stronger ice and fighting moves, but they usually have side effects like stat lowering, lower accuracy, or charge time. Especially if you hit something that's actually WEAK to those moves… (and fighting is super effective on 5 different types, and ice hits 4)