More than the obvious effect of plummeting Epic prices, which is not objectively good or bad, but rather a matter of opinion. It creates a 'jackpot' effect. In a very real sense, it is high stakes gambling (for FS anyway). You are risking far more than the FSP lottery that was removed long ago. With, say 2 sets of ingredients for any given epic, you could end up with 2 epics, or 8.
Omacaz is a relatively expensive lottery ticket.
It's not even that it's a really expensive lottery ticket. If you've got enough capital to invest into epics, there's no way you'll make a loss. The save rate on the Omacaz is just so high that it's basically impossible to lose money if you use enough items. This effect is compounded even further on the gnarled scarab epics, as mentioned above. Sure, it might not be worth it with 2-3 rings/necklaces, but if you're inventing 10, 20, even 30 ... the profit skyrockets as the individual cost of using the potion per epic decreases and the amount of things saved increases.