The combination of competitive relevance, one of the most popular Legendary Pokemon from one of the most popular generations, and absolutely stunning Galarian Gallery artwork makes this a triple threat that appeals to virtually every type of collector in the hobby
Proliferate, graveyard matters, +1/+1 counters, mill, and self-mill all became angles we could design new cards around as well as find reprints for
Pacifism and the variants above I'd never run, but Darksteel Mutation gets the job done, son
While naturally costing just white mana, Kenrith has five abilities, each one with a different mana cost and color commitment, to help give you an advantage in your game
For competitive players, most cards have been power-crept, so buying singles is more practical