First off, Savage content should not just be a single battle. It should be like dungeons. There should be 4, 8, and 24 man variants where the battle is broken down into several parts and the bigger the group, the more difficult it is. Right now, Savage content feels like just a chain of instant death conditions more than anything.
Mistakes and large scale AoEs should add things like vulnerability stacks instead of just flat out killing people. Multiple mistakes would lead to eventually a one hit kill, but no one single phase of the boss should be able to instantly kill someone just by say failing a DPS check. Should they be punished for it? Yes. But should it instantly wipe a party? No. I think tis will emphasize skill over equipment and allow players who are sufficiently skilled to clear the content with much lower item levels as well. Add some randomization to what type of AoE attacks a boss will use during their attack combos so that it isn't always as predictable.
This way players are punished for mistakes, but it doesn't mean it's an instant wipe and starting over. It gives groups an opportunity to recover by avoiding additional mistakes. However, making more mistakes will lead to the eventual instant death.
However, I think raiding is forced to a degree because it is the only place where the end game content is available in MMOs nowadays. If you don't raid, it means most of the patches are pointless as they tend to only add new dungeons and little of anything else. Much of the high level gear is only available from raids and players are locked out of some of them from Duty Finder unless they can find a raid group on their own server.