Well, "use" is the wrong word. After competing most quests and collecting most shards i had enough skillpoints to satisfy my inner autist and skill the whole crafter lines (well, except the keen eye …
No, I've never used this passive. Since all potions I make have positive effects on self, the only way I could see it used is if I was trying to save up on certain alchemy mats, and use a combo with …
I don't even know how to make a potion with negative effects. But I have the passive unlocked because the page looks ugly with one of the passives greyed out.
Simply because I don't make potions for others or sell any on guild stores, so when making stuff to use myself I like to have options to use cheaper reagents does not affect anyone else.