In my experience, seat kickers tend to be male, adult, and
short--and only seem to do it when my seat is in its fully upright position.
A few months ago, about halfway through a completely full UA Sh*ttle flight (all 31" seat pitch in Y), the woman behind me asked if I would move my seat forward so she could feed her infant. OK, that's reasonable.
My height isn't in my legs, and UA's seatback-mounted tray tables, when lowered, move very little, despite what the seat does.
Excuse me, person-in-front, would you mind reclining so my in-seat video screen will be positioned at a better viewing angle?