Removing the legendary rule would terrorize every format even worse than removing the planeswalker restriction. Just think about the possibility of double Teferi, Time Raveler or Questing Beast, or more than one Sheoldred, Whispering One; any one of those cards can flip the table, but without legendary, there'd be a million of them. I'm just not sure what the benefits could be against that much brokenness. Considering all the strong legends lately, it needs to be more restrictive, not less.

My recommendation comes with a Unique mechanic that can be applied to the small number of cards that need the restriction. Note that the most played format right now is Comnander which is singleton. Adding more cards with legendary as a marker is mostly upside for Commander.

Who designed Sheoldred, Whispering One? And if I sent you a copy with a self-addressed envelope, would it be possible for you as well as that designer to sign it? I understand that you probably have more pressing things to do than to track down somebody for their signature on a card, so if not, I'd be happy with just your signature.

It was either Ken Nagle or myself (and possibly a combination). Always happy to sign cards. If you send it, I’ll figure out who designed it.