I have no problem with an increase, but make it gradual. Like Kevin mentions, faze in the increase. Whether it be as he suggests(moving to $35), or instead charge $1 xtra per team for the first couple of years, then move it to $2 as the number of unmanaged teams are scooped up.

While many owners will keep 15 teams, many may drop 10 of them. Combined with an unknown knowledge of how quickly teams will be picked up could result in a disasterous situation.

While you may get 20 owners taking on two or three more teams, you might also see 10 founders dropping 5-10 teams, resulting in an increase in unmanaged teams.

So I say go with an increase, but make it either $35, or make it $1 per team. Then we can relook at the situation later as the number of unmanaged teams gets to 1 per league.