As much as this has been repeated when this topic comes up, I don't think it's a good answer. Threads like this popup because roulettes aren't designed to be fun and since this is a video game, that's a massive issue. Rewards don't excuse that. People want the game to be better and I don't know why anyone would want to argue against that request.
Being boring doesn't help anyone. It doesn't help people progressing, nor does it help people leveling, nor does it help people waiting in queue times. The roulette system is not a perfectly optimized solution that can't be tweaked or replaced and yes the roulettes would remain roulettes even if people could exclude content from them, which is a feature already built into roulettes since there is no roulette that includes all content.