Low Blow is useful for stunning regular mobs in dungeons. I use it all the time to mitigate large AOEs, final stings, bad breaths, or when there are just a few enemies left. It reduces one of the 3 enemies' damage to zero, while the party quickly destroys another enemy. The result is only 2 or less enemies attacking me at any point, giving the healer no need to heal me, even in a lot of leveling dungeons where everything hurts more.

I also use it to stun a regular mob if I lose aggro out of tank stance or to keep it positioned correctly when I need to move.

You can try and argue these things don't matter, but it's an oGCD that doesn't bother me to weave in. I find it stops me taking an amount of damage that might prompt some healers to heal.

Silence is used for certain hunts, so they have to keep it in for those.

It's true that we just wouldn't know if silence worked on anything other than hunts. We assume stuns and silences don't work on bosses, so if they designed a mechanic with the idea of it being stunned or silenced we might never figure it out without these UI changes.