As thm /blm as my main since beta....i can understand ur frustrations with the new battle system and mp. Its a valid concern, however its not too hard to get accustomed to the new style so you have a decent mp pool. I think thm/blm was redone this way because the class/job specializes in BURST damage not just by spamming spells over and over. I remember before the battle reforms my thm never ran out of mp it seemed, especially with absorb mp. Just try and pace yourself and you should be ok. Spamming spells may do a great deal of dmg, but once you are completely out of mp you can be in trouble, so pacing yourself is key. Hope this helps^^