No matter what you pay for the card, the mana value doesnt change (except for improvised spells with X in their casting cost)
It creates a consistent layout across collections
Brand-new mechanics are hard to evaluate, after all, whereas established effects have more of a track record to refer to
Try Coercion, Dark Inquiry, Diplomacy of the Wastes, Doomfall, Memory Leak, Memory Theft, Never Happened, Perish the Thought, Reckoner Shakedown, or Toil of the Invasion, if you just want to pluck a card of your choice out of an opponents hand for three mana
Theres also the likes of Sol Talisman, which is basically a Sol Ring that takes three turns to actually come into play
The fire flowing outside the frame and off the card adds so much to what could be, in the case of the majority of Pokemon cards, a minimalist card design