Removing existing Classes at this point would just be a waste of time, since they'd have to rewrite their entire storyline for Classes/Jobs to accommodate players being Dragoon from Lv1 instead. It's a lot of extra work for no real gain at all.

The only change they should make to Classes is merging them all into a Freelancer style Job, since that can retain all the existing lore and potentially be viable at endgame if they go with the classic "Gets stronger the more you master" trait the Job has always had. I can't even imagine it would be too hard to implement, considering a Freelancer Job would effectively just be 1.0s Physical/Skill level system.