The debut of Legend cards (Lugia & Ho-Oh) offered something bold and collectible, while Prime Pokmon introduced a new kind of power creep
From a design standpoint, if your opponent is able to kill it before it can attack, it's essentially the same as it having pseudo-haste and dealing seven damage
Eevee Heroes Eevee is a beloved Pokemon known for its ability to evolve into multiple different forms
And best of all, you only need 4 copies of any card ever because all your decks share the same virtual card pool and you dont need multiple 4-copy sets of the same card if you want to reuse it in other decks (which is another reason why the secondary market is so well supplied)
For one thing, the mechanic has a ton of different options, and getting players to venture three or four times every turn would not only melt their brains but also take away the feeling of progress that's so much fun in going slowly
Play Martyr of Sands, Soul Warden or Soulmender instead