Purification pill as a goal itself is ONLY when you have maxed out everything. Ammount o power you get through a single pill is abysmal. Lets imagine dream scenario, where you have lv10 refinement on an item and all golden purifies with 100%, which in total gives you 665 ini/crit/combo/injury/control and the same 665 via purifies, so a total of 1330 stat. Single pill will give you 13,3 of each stat, which results in like 30 power increase. 30, considering u have all golden 100%, which is pretty much unobtainable.

Since it requires (at least so far) always either 30/40k recharge/spend, it's ok if its an addition, but not as a goal itself.