It might stop you from complaining about being in the same zone all the time.
I know there are less people there but like I said, it was the players choice to stay in those zones. Just like in FFXI it was the player's choice to stay in Valkurm. Yes, there are game factors affecting this, for Valkurm it was closer to San d'Oria and Bastok whereas Buburimu was only closer to Windurst. In FFXIV, Uldah has more popular guides, this made more people use the market wards there, so people stayed around that area.
The game does try to help people go to other areas, you can teleport there in an instant but people prefer to come on the forums and complain about the lack of airships instead, despite the airships in FFXI being rarely used after outpost warps became available.
I do agree that giving players control over the difficulty level of leves causes a problem but I don't think making them as a solo only content is the answer. Party play is weak enough already without removing the only reason for it. I think it'd be better to either have leves with a recommended party size and having the difficulty rating fixed or having the difficulty level set automatically based on the current party size.