I also wouldn't mind having the leveling 80-90 dungeons included, even better if they would be scaled up. Especially since these are usually better than the ones we encounter at expert anyway.
Or even leave every lvl 90 dungeon at the roulette so that at the end of the expansion it's less dreadful (though by then there won't be much reason to cap tomes anyway).
I agree that it's weird how I barely touch the current expansion content while doing stuff such as roulettes, unless you're talking about lvl 80+ roulette or expert roulette.
If I'm doing roulettes, I typically do trial/normal raid/leveling and expert - the rest are boring to a point that's not worth doing no matter the rewards or simply not worth doing because of the rewards.
I'll never forget a day before EW release my friends and I landed on a shadowbringers dungeon in leveling roulette, and we cheered because it's so rare for it to happen.