The First Sliver and Sisay, Weatherlight Captain are assuredly more powerful cards, but they're fairly interchangable with other five-color legends in their respective archetypes
Its activated abilities can't be activated this turn
2: Exile target creature you control
They kind of learned their lesson on that one, but not really
On top of this, players can level up their Pokmon and improve their abilities and statistics, helping them get closer to their ultimate goal of defeating the champion of the Kanto region
It drives up the price of other Pokmon TCG products, makes it more difficult for newcomers to get into the game (which is the entire point of a promotion like this), and it certainly puts the game outside of the price range of its target demographic, actual children