Best thing I can think of is making the cap and tomes class locked. So if you max tomes as a paladin you can switch to monk to get tomes for your monk class. Of course with this they would have to implement a filter when buying gear as well is glad/pad can only buy glad/pal gear and cannot buy conj/whm gear that way it still puts a pace on how fast you can gear up each class and you can't have players in full AF2 gear in a couple of days by buying pal gear with tomes collected on a Monk.