That's not card advantage, but it always comes in handy
When a player cannot untap lands or creatures, their turns technically still happen, but functionally, they may as well not exist
You cant fill your deck with top tier spells like Shivan Fire, so youre encouraged to chain cards like Opt (which is durdly), Divination (which is very durdly), and Radiating Lightning (which is fine, but unexciting)
The Bobbleheads repeatable nature helps compensate for the costly investment, but locking its ability to sorcery speed means we wont be able to use it to save key cards on our board from board wipes and targeted removal
I suspect that collectors are at work, wanting the FEA versions of legends from our favorite games, but I cant confirm that at all