Solitude stays relevant in the format as long as powerful creatures are being played
A 3/2 flyer that effectively couldn't be blocked was pretty much a bomb, since there were few removal spells, fewer fliers, and virtually no tempo in this format
Three different Final Fantasy cards are still great, but their impact has been most noticeable in one format: Commander
Circling back to TAUC costs, you could argue its actually even closer to free than other alternate costs: life points and cards in hand are expendable resources, and (at least for drawing cards) somewhat expensive to replenish
But Im sure there are going to be builds that are counterspell dense, and that seems less fun
It was pretty popular but only shows up on a handful of cards, so there isnt enough of it to really make an impact