Both because the IP is strong and nostalgic, very important in this age of Magic pandering to the folks in their early 40s, but also because its going to sell alongside the next Miku installment, and that will be gone quickly
As a consequence of these numerous relevant threats which survive Lightning Bolt, any deck (besides Burn) which can enable Delirium like Deaths Shadow, UR Murktide or 4c Yorion, is better off playing Unholy Heat over Lightning Bolt nowadays
Heres a more succinct breakdown: Everything in black and white will ALWAYS be black or white in the actual Dot Code
When this Aura enters, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with this Aura." Return enchanted creature card to the battlefield under your control and attach this Aura to it
On resolution of Arc Trail all 3 damage will be redirected to the bear that will then die heroically the next time SBA are performed