Back when RO's level cap is 99, some individuals leveled their novices, first jobs to level 99. Just to keep the aesthetic look of the first job sprites. Not to mention the special aura that came with it, and also bragging rights: "hey I'm max level and I accomplished this unique challenge."
It's a unique way of experiencing the game, although this method and proposal seems more of a band-aid solution to the main motive of having a first job class to run around with. Ideally we just have alt sprites for first jobs, and everyone is happy, right? Unless I misunderstood.
Something to keep in mind, leveling in the early 1-99 is incredibly fast, removing the limit could cause some accidental level up for a select few. ie: Leveling past 99 when I want to rebirth/change jobs/etc.
Perhaps a command or NPC, similar to @lockjob would be a good preventative measure, if this gets implemented.