Yup this is a great ability to use even when you are not in range of an enemy. You might have missed the 2nd good reason though, just above this one - the 20% speed boost. Great for repositioning yourself or also retreating while taking reduced damage.

> "still get destroyed because, well, they can and do return fire"

One option is to use AOE weapons. The ability can stun enemies behind walls or obstructions while the AOE weapon gives you a chance to damage them with less exposure than normal. So if they don't have AOE weapons the partial stun can still be useful. 

Thanks for sharing what you learned!

The most annoying practical disadvantage in Blizzfrost's ability is it activates in a circular plane (so it won't affect enemies which are standing under the mech (but the ability is technically coming out from its skirt, and it should hit enemies wherever it is) 

Most common in Elon Station Gray (the moon map) where your blizzfrost's ability won't hit enemies if it's on the inclined pathways

Yep. Complained about that myself. That's why I use the ability for the speed boost and damage reduction.