This may be a bit off topic, but I think the issue is less about casual/hardcore but about variety and play style.

There are a number of activities to do up to end game, but we're kind of stuck with extremes/coils. Other types of difficult end game content would add to the variety and people's play styles. For example, and this may be a silly example, Timeworn Maps with extremely difficult traps or new zones with terrifyingly high level mobs. Then again, there would need to be a reward worth it to bother with these alternatives and I would not know what that might be.