Because your opponent probably didn't bring the figures required for the Atlantis Attacks ED or the Bat-characters for No Man's Land, etc. That's a different level of nerf than both players not being able to carry or taking extra damage on certain attacks.

If fun is the objective, the best way to handle EDs is to have a tournament announced where everyone knows "hey, we're using this ED for all the games." Gives everyone time to take a look at the ED. If there's certain build conditions or advantages, they can build their teams around that. If there's extra set-up involved (like with Infinity Gauntlet), everyone can be prepared to expect that and maybe the judge will schedule longer rounds to accommodate that.

Come to think of it, Planet Hulk would work real nice now with the influx of generics...

Which is why there should only be that caveat to ignore if and only if your team can't be used with that ED. Or you could just be allowed to designate one of your figures with that Pre-req. So your HoT Cap now has the in place of the .

Either way it would make the EDs more viable.

I'm usually referring to the ones like UCW, Time Bomb, Dial H for Hero, etc...