Brood War was famous for 7v1 comp stomps being very popular in custom games, and it was obviously huge competitively, it's the super hardcore competitive RTS, even if it wasn't really planned that way.
The PvE comp stomp crowd seems to really like the co-op mode in Starcraft 2 that was introduced. To the extent that they have complaints, it's mostly that they wish there was even more stuff in it.
I think for the most part, the things that competitive players and casual players want aren't really at odds. They're usually orthogonal desires.
But what does exist, are a lot of people who say "I want to play RTS, but" and will never be satisfied. Like, there's always tons of people saying that they just want an easier to play RTS than Starcraft, and there's been tons of those, and hardly anyone plays them.
AOE4 has been an interesting journey for someone that prefers the good ol fashioned comp-stomp. It wasn't long before I was easily taking on 4 of the hardest AI and easily stomping them on certain maps, like mountain pass. But, they've progressively made the AI into a much tougher opponent. It's actually challenging now, and I'm only back up to 2 hardest, 2 hard with AI teammates on the same map. Can't speak to pvp; I've not tried at all.
Having a semi-structured form of this would also be really good imo. Starcraft 2 sorta has this -- there's a UI section similar to ladder that pits you against increasingly harder AI's, but it's just a single track and doesn't go far enough imo.
I can easily imagine a set of 'tiers' of challenges, where the bottom tier is super easy stuff for beginners and then each tier up increases the challenge until you're fighting a bunch of hard-level AI's simultaneously or whatever. Or maybe a Mario Bros-style world map that has various different challenges in different directions.
