I feel like the solution to make other raids as desirable as those two is fairly simple. The ilvlsync of 130 can be lowered to like 100, 130 is just pure overkill.

Players could enjoy the raid mechanics more, maybe even fully. People who limit their ilvl end up in 24raids that take as much time as other raids then, there wouldn't be a benefit to do it. And we would see different raids again.
I wouldn't mind playing a few minutes longer, if I actually am required to use my brain for the mechanics for once.

Other solutions seem to complex or too hard on players imo.