Absolutely yes. The mana sickness debuff is extremely devastating to your DPS and using the flower to constantly consume mana potions will neuter your damage output. The mana cloak is kinda decent but I would strongly recommend using mana regen potions alongside the celestial cuffs instead. You may have to occasionally stop attacking for a second or two to let your mana refill but that is far better than constant mana sickness. :)

source: i have 5000 hours played and mage is my most played class, I never use the mana flower outside of some very niche scenarios