Nope it would just ruin it for new players when everything around them just explodes in flashy aoes and all the stuff you get with lvl 90. Not to mention that balancing the jobs so they won't just blast through old dungeons on sync would be a terrifying nightmare for the devs. Since that way you need to also make the actions that are available at that level also weaker since the new players should be on the same powerlevel as you.

But if you want to use all your skills then don't do roulette and play current dungeons. BUT MUH EXP you would scream now. Doing roulettes is helping new players do old content, it is not designed for you to farm exp. That is the reward you specifically get for it, yes. So if you are unhappy with that nobody forces you to use this system.