The original point of level sync was to prevent veteran players from speeding through content and taking the experience away from the newer players in their party. The biggest example is the 2.0 Main Scenario instances. The lack of item level sync in those means that it's possible for a party of 4 overgeared veterans to speed ahead, lock out the 4 newbies from the boss fights, and beat the instance without them, ruining the newbies' experience of the dungeon.

The best of both worlds would be for SE to increase the Roulette rewards, but split the High Level Roulette into some smaller roulettes, and then change item level sync to be more appropriate for the easier dungeons. Let's face it, ilvl110 for WP and AK is way too high. Even syncing down to i70 wouldn't make the dungeon that hard. With more roulette categories, veterans can run through the multiple roulettes with level sync and increased rewards, and the DF will still have a large pool of players to match up with newbies. The veterans that want to continue tome farming can speedrun the highest level dungeons as long as they want for the best rewards.