Removing MP would require a drastic rework of the entire game. As removing it would break every healer class and all the mages. All healing and reviving would have to be changed to be cooldown based as there would be no detriments to heal spamming or people dying in any fight without a enrage mechanic otherwise. You would have SCH and AST players just spamming shields to null damage if they did not have to care about mana at all.

TP was only ever a concern in 1 situation: AoE pulls. Outside of then it regenerated faster then it could be consumed unless you were playing a class that could achieve ludicrous skill speeds to actually outpace the regen.

Hence why it was not an issue to remove TP. TP itself was nearly as useless as the non royal road Spire card was. Both were only ever a concern/use in 1 situation that was only ever in normal dungeons.