There clearly targeting explosions. But, plenty of things generate shockwaves so really expensive active sound dampening or just High frequency vibration dampening.

There are probably far more cost effective approaches, but quieter dental drill for people that just hate the sound. There might be a safety advantage for quieter bone drills etc. Instrument isolation for scientific experiments.

I first thought this was for alleviating shock waves in supersonic flight, but I guess they've been doing these kind of things for a long time

Hardening civilian infrastructure?

Flight MH17 can be an example.

MH17 was downed by the shrapnel from the missile, not the shockwave. The BUK missile's shrapnel number, density and speed was designed to take down, in particular, armored planes like A-10 (into the face, not from behind), so the plasma expansion speed to affect the shrapnel should be on the order of several Mach, something like jet exhaust for example.