The mechanic adds a lot of complexity, but not in a fun way
The Reaver Cleaver - which gets the award for coolest card name of the past few months - turns your combat damage into treasure tokens, and with the amount of keyword heavy creatures in the 99 should have no issue finding a nice target to equip to
Its only recently that planeswalkers inched over the line of being present for more than half of Magics history, which shows how long the game has been going and how heavily planeswalkers have impacted set design, format strategies, and gameplay
As for what a waifu tax is, it is the concept of a card or collectible demanding a higher price tag due to the art showcasing a character deemed as a waifu
Damia, Sage of Stone Commanders that provide a source of cards advantage are always powerful, and Damia, Sage of Stone can draw you tons of cards