How about a weight cutoff then? Sat next to someone who was easily> 400 lbs in an exit row. No way he could easily move and open the door in an emergency.

Lets keep pushing it. No little old ladies either. No way they can open the door.

Of course we wouldn't want any teenagers either. Can't be relied upon.

The sad truth is, most of the people that make complaints like this have an underlying bias or just want the extra legroom for themselves.