Obviously looked upon with some disdain by those with limited inventory. But if you have the space...
Cheaper than Brachyura Earring by a long shot, has the same properties, and does not stack with the earring. Arguably better due to the Regen effect (especially if you have this in your idle set). Even some mages can use this instead of the earring if it's in a slot that swaps out to a no-mp potency ring on cast.
All in all, it means that almost anyone can afford the luxury of slightly enhanced Pro/Shell spells.