You get more residum each week, the mount is gonna be all +15s time and you still get bragging rights over leaderboards, but like I said they could make an official season leaderboard. The tmog thing is not a bad idea, but I don’t think it should be over +15s. The class stacking for +20s is insane. More than 80% of the +20 pool is only 4 classes.
5 ilvl lower, close enough 
Rng is rng for everyone, and they are making it better next expansion (by adding choices I think they said). And item design can be awful in raid too. Remember that ghunn trinket yea…
I think the biggest problem M+ wise is that they need to do more dungeons each seasons. So they can get new items out, feels boring to farm the same items all expansion.