I have a suggestion that would benefit non raiders and make primary Open Worlders happy.
Create Open World non instanced zones where the Raids are stationed on the map, the bosses would be set to be on Par with Legendary Bounties, and the rewards would be the same as Legendary Bounties with no option to get Legendary Armor.
(You can Zerg your way to Legendary Armor any way in WvW so no worries right?).
You guys get to keep your Raids with no difficulties altered.
Open Worlders are opened up to new Legendary Bounties with mechanics tacked on that are close Approximations that change each encounter by random.
No new assets really need to be created, the Raid Maps are already there, the boss models already exist, the Legendary Bounties with their mechanics are already there.
No new content needs to be created, just utilized in a new option.
It's a great option, you guys can do your own thing and never have to mix with people like me.
win win solution.