If you're grinding the same two EX dungeons then go do something else? Alot of things award Eso tomes, personally im capped by Thursday at the latest doing 2 EX roulettes and doing PVP... only time i bother after that is to help my FC members by lending them my tank queue time. As of right now im sitting at just less than 300 eso tomes after a single EX roulette and a few hours of PVP with my LS. If i feel like it i can cap my eso tomes tonight, a day after reset with no real "grind" involved and i get to Rank up to boot.

As for the roulette's:

Raid Roulette: This is fine and all until you keep ending up in LOTA with people who don't know what to do.. I and probably many others wouldn't bother queuing for this after awhile just to more than likely end up quitting and eating a lock out...

Extreme Roulette: Considering i don't bother with Trial roulette anymore because people can't seem to do the EASIER versions of Primals (if i even get primals, mostly fail parties at Steps of Faith and Chrystallis), i wouldn't queue for this either.. The requirement to complete it to unlock the roulette is pointless too because of Unsynced runs people can just get carried through.. I mean.. i had someone in i190 gear who had clearly done Levi EX before and had NO IDEA what to do :L as long as people can get carried through the EX trials i wouldn't bother wasting time with this either...

Random Roulette: Could be a good idea if people are desperate to do the odd trials like Hildebrand, but chances are we won't get those kinds of trials and will be shoved into something easy with lv synced players... Not really against this one, but i wouldn't do it personally, i'd just ask my FC for help clearing things like hildebrand or throw up a PF if not.

Main Scenario: I doubt they can convert these dungeons into a solo experience without ruining the actual experience of reaching the end of the main story line, it would involve re-doing cutscenes and removing parts of the dungeons just for the sake of it which is a waste of time and resources for SE. Without this "specific" roulette there'd be far less people running these for the new players, but as of right now its still doing its job in getting enough people into these instances to get new players through. Besides you trying fight Ultima Weapon solo and see how it works out