I'm seeing this more and more as fights tend to be full these flying days.
About 1/2 way through the boarding process, the FA's start announcing that only the larger bag in the overhead and smaller bags under the seat in front of you since "We are running out of overhead bin space".

I'm usually goofing around with my laptop carry-on bag anyway so I put this under the seat so I can get to it easily during flight. I'm only 6'1" so I deal with it. We all have to share what little space there is.