Yes, I use it when I know others are shooting from behind me.
So few people crouch in first line.
That's because game developers usually make friendly bullets pass through players, instead of brutally murdering them or making said bullets disappear into oblivion. (I think you could disable this in KF1, or it was never enabled to begin with... I honestly don't remember.)
I found zero reason to use crouch in KF2 so far.
Then you are a terrible team player.