It just seems to be that you have to have a whole lot of time on your hands to commit to learning to play one pocket well, and to play serious one pocket
matches against other one pocket players. For many of us who, due to other commitments, only have say 10 total hours a week to play pool in 2-3 sessions
per week, for the benefit of my overall game, stroke, shotmaking, positioning and defensive play, I would rather spend that time playing rotational games
or 14.1.
In a 3 hour session of playing a serious 9-ball match against another player of a similar skill level, we will likely play +/- 25 total games, pocket 200-250 total
balls between the two of us, playing maybe 50-75 safeties between us.
By comparison, in a 3 hour serious one-pocket session against a similar skilled player, we likely would play no more than 5-7 games, pocket no more than
60-80 balls between us, while likely playing 300+ safeties or two-way shots between us. There is just no contest as to which of these two options I would
choose to spend my time playing, in an attempt to keep my overall game up, everything else being equal.