To clarify, a big reason why FFXIV so so successful, is that 1-50 is like a giant tutorial, that teaches everyone how to play.
They still want everyone to go through that tutorial, its essential to having a group of lvl 50 players who are at least semi comfortable with their job and class. It is very likely they just didn't have the time and resources to fit that into the new classes, and also the lore would not make sense for them to do so.
I mean, it was the same thing with WoW when wrath of the lich king came out, you needed a max level character to make a deathknight.
They still want everyone to go through that tutorial, its essential to having a group of lvl 50 players who are at least semi comfortable with their job and class. It is very likely they just didn't have the time and resources to fit that into the new classes, and also the lore would not make sense for them to do so.
I mean, it was the same thing with WoW when wrath of the lich king came out, you needed a max level character to make a deathknight.