"Totally disassociate Arcanist and Summoner" the OP says. And yet, pet attacks listed for Arcanist still include the word "Egi" ...

"Merge Energy Drain/Siphon or Fester/Painflare" into one button the OP suggests, ignoring the fact that one is a single attack and the other is an AoE.

The reason this can never become reality? SE would have to write 40 levels of new jobs quests specifically for Arcanist, and rewrite 30 levels of both Summoner and Scholar new job quests in order to make it work.