If anything, I think the history of things like phyrexian mana shows that Wizards does learn from their design mistakes
Then again, it recently got reprinted in Murders at Karlov Manor , which made the price drop significantly
There werent a lot of planeswalkers around, and at four mana it could be clunky and lead to significant tempo losses against Lightning Strike, Petty Theft, and other commonly played interactive cards
In the same way, you cant pay a cost that requires you to discard a card if you don't have any cards to discard
Pairing it with something likeUltron, Artificial Malevolence, which lets you copy artifacts by paying two mana and turning them into creatures, could get out of hand quickly
1Void Rend