The only positive things I can think of is if you had magnetic boots with no need for a binding you could change your stance super easy, and skating would be easier, and of course "strapping in" would be easy. But you'd have chunks of metal on or in the board.
If there would still be a binding plate or something mounted to the board the only advantage would be stepping in.
But realistically seems like it's damn near impossible. If it was an electro magnet like in junk yards I can see it releasing when you want it, but you'd have to have a battery somewhere on the board or on your person. When the battery died you'd be a no boarder.
IMO it is not a better idea than straps.