Adoption by whom? Not the hundreds of 24/7 2fort servers, because the players there love the map because it's a deathmatch. Snipers, spies, soldiers and demomen alike can have some random fragging practice while pyros, engineers and medics learn the game. For the server owners who like balanced maps, why would they install a modification of 2fort, which they've likely entirely abolished, rather than a whole new map, aside from the "wow" effect of playing on an acceptable version of 2fort?
Because there are about 40 active 2fort modded servers, and none of them run the best one which is revamp.