An extreme roulette is one of those... Great on paper but won't actually work well in execution. In theory, it would be nice, but the reality is that people lack the patience and much more lack the skill to do an extreme primal (Well actually can, but the issue is when you put this into a roulette where the mechanics will be diverse. You can know some extremes from the back of your hand and then others may require considerably more time to execute again), within the given time frame. You have a grand 60 minutes to complete the duty when really most people would require that and then more. It'd be an exercise in wasting time with the infrequent "Hurray, we did it!"

All it takes is some bad rolls with an extreme primal to be in an encounter you know nothing about. Current roulettes work simply because you can clear the encounter way within the timeframe. 99.9% of the time you know that a trial roulette will take 7-20 minutes, equally, you know that a dungeon will typically take 12-22 minutes. In an extreme primal roulette, more often than not you would be in a position where it's an exercise in wasting time because you'll more than likely be spending the entire lockout on it.

This doesn't even take into account what rewards would you lock behind it to even make it worth the time?