On the off chance that you actually read this, whoever told you that the roulette system was put in place to save players from over grinding was mistaken or somehow confusing it with a 1.0 FFXIV system that actually reduced your exp gain (think reverse rested exp). Exp limiting systems no longer exist and haven't since 2011. Roulettes are there to encourage high level players to run content beneath their level once a day to help lower level duties fill up; new players could not progress through the story otherwise.
If your goal is exp, just queue up for the closest odd-level dungeon to your level after leveling roulette is complete for the day. At 58, that'll be level 57, 'The Vault'. This will award you with plenty of exp for your level and should only take around 3 to 4 runs from 57 to reach 59, the next dungeon's level range. Dungeons award all their exp on the endboss nowadays, so if you have food for the +3% or a Free Company/Heat of battle scroll, make sure it's on by the time you beat it.
You may be slightly undergeared for it at i124 because it's tuned for players around i136, but you can still queue and it'd be no trouble for a WoW vet to handle, especially playing a DPS role. This will also quickly fix itself as the dungeon offers plenty of i142 maiming and slaying gear a DRG can use scattered in chests throughout, and, as with every leveling dungeon, you're guaranteed to get 1 piece of gear good for your current job that you don't already possess when your complete it.
Outside of dungeons you can do FATEs in a zone like The Churning Mists as you wait for the next pop. Dungeons and FATEs offer limitless, simple battle grinding exp and have been among the fastest ways to level since 2013.
Just in case you haven't unlocked The Vault, which I don't think is the case but I'm not familiar with how gear works for a player leveling today vs then:
Now, you may be between patches 2.0 and 3.0 in your MSQ progress in which case you may not have this dungeon unlocked yet. All MSQ from 2.x until 3.0 was devised for a time when the level cap was 50 and thus doesn't award much exp. This can make it feel like you've hit a wall in your progress leveling, but this is a fundamental difference between WoW and FFXIV. In FFXIV, MSQ progress (and sidequests that appear along the way) is what unlocks more content, not your level. You could be a 90 DRG and unable to participate in 'endgame' if you didn't get your MSQ done to 90 as well. So, try to gauge your progress with the MSQ instead of your exp bar, the levels are largely meaningless if your goal is to get to big fancy bosses, dungeons and raids.
This can be a pretty big shift from WoW, but most ex or both WoW players of FFXIV will attest that the story doesn't waste your time too much, especially as it ramps up towards the end of 2.5, so hopefully you'll find it engaging. The rest of the game is a lot of talking to skip through otherwise.