I dont really understand why druid and paladin off tanks are not wanted for raiding?
A feral druid brings critt buff, inntervate, rebirth, sleep and roots. Feral druids can swap to cat when the mob that needed off tanking is dead (major domo, lucifron, etc), then the feral druid will do better dps than the fury warr in tank gear.
Feral druids are great resistance tanks.
Paladin If you go 20/31 as a paladin you be a great off tank and even MT bosses if you know how to manage your mana, as MT you can remove debuffs which would otherwise kill you with cast/remove divine shield macro. When you are not MT/OT you can throw on your MP5/critt gear, you already have the most important holy talents anyway so you can actually out heal deep holy specced paladins( when it comes to raid healing, not MT healing). You bring blessing of sactuary which reduces damage from all sources.(great for all fights with alot of raid dmg). When needed you can use blessing of sacriface to reduce damage on tank before a hard hitting boss move, combine it with divine shield and you wont take any damage, and lets not forget lay on hands and blessing of protection?
The dps paladin is very decent dps and can support with blessing of sacrifice, blessing of protection, blessing of freedom, lay on hands, dispell, etc.