I have one outcast pc that I rolled for a NCE and, well, ocasionally I hop on. That said, limiting access to dungeons (in a server that constantly feel crowded and hitting a dungeon in high spawn feels like winning the lottery) seems bad.
Outcasts should be played for rp purposes, imposing limits to game content will lead to less people providing this important part of the setting.
If possible, I'd suggest, at least, that the "caravan room" system is implemented, allowing calibans to enter invisible and the party to pay the ferry.