This is about making mages too overpowered.
Mages have a much bigger mana pool than EKs have health.
- Druid / Sorcerer level 200 has 5,850 Mana
- Knight level 200 has 3,065 HP
What are the implications?
- For short periods of time, a mage can tank more than an EK. (in long periods, the extra healing from Supremes will surpass the MANA/HP difference)
- If mages had Supreme Mana Potions, then they would basically be immortal in most of the situations, and able to tank more than EK's, since they have bigger mana pool and a Supreme Mana would heal the same as a Supreme Health
- Mages are already able to do almost anything with Ultimate manas, since they have such a big mana pool, they can solo hunt library at level 300, they can solo run most of the quests, etc...
Besides that, at solo hunts, an EK needs to pot HP and also pot MANA, so he has to use 2 kinds of pots. If EKs didn't have supremes, they would have to use a considerable extra amount of Ultimates, meaning they would use less mana, leading to a bad hunt, because an EK without mana is just useless. So EKs NEEDED a stronger HP pot (and even now they are still the weakest vocation when it comes to late game sustain / solo hunts).
Mages do not need a stronger mana pot, and that's why don't have it.
PS: All of this is based on my knowledge of the game and may be incorrect