I agree both of these are on my list of small but very annoying details of HBD.
Would be nice if there was a warning screen before the season starts any time a roster move is made and a team at any level has fewer than 20 players. But don't block the move. It just adds needless time to playing HBD.
Same for not being able to demote a ML player and make inactive in one more. Stupid waste of time to be forced to deactivate another player, as that usually messes up lineups, defensive replacements, etc.