You typically get several Commander staples in them, which add up to what you paid for it
Sage of the Maze is pretty niche in that its a Gates-matter kind of card, but on the other hand, its also a card thatll slot into many decks, because Gates-matters fits in so many decks too
You'll be more likely to hit your land drops
On its own, this is already incredibly useful yet Panoptic Projektor gets even better with its Panharmonicon-esque effect
While the Phyrexian-language cards have proved popular for collectors, their inclusion in Draft boosters has been criticised
Rest in Peace, Dauthi Voidwalker, and Leyline of the Void are a few prominent examples of effective graveyard hate