Why is everyone so worried about minions going down like wheat? That's what they are supposed to do! It's cinematic.

Blast only triggers on targets Engaged with the main target, which is almost never going to hit every minion anyway. It's really not overpowered.

If you want uber-minions, then don't have Blast trigger on each one. I'm pretty sure it's your game after you pay for the book.

You really don't even need to trigger Blast in some circumstances, even the book points out a GM may simply rule if the targets are all in a room or other enclosed space, they are all subject to Blast regardless. Whether a GM chooses to apply the Blast effect over the Minion group using the grouping rule or individually is their call I suppose.

I don't read Blast as activating without the Advantages. (In fact there is a paragraph to explain why it doesn't hit everyone narratively when you aren't able to activate it.) However, it does say in tight spaces, or small rooms, everyone doesn't necessarily need to be engaged to be hit if it does activate, and I use this rule all the time in suitable spaces.