Games grow, times change etc.
When XI was new, the low/mid levels mattered because the majority of content was at those levels. Stuff like BC40/60 were in demand because most people didn't reach the cap and the game wasn't really focused on endgame more it was on giving people a variety of stuff to do at all caps.
Today's XI is centered on first reaching the cap then enjoying the various content the game has to offer.
All of the content is at the top so why would SE invest resources into making the EXP climb harder when evidence shows this game is painfully topheavy, not taking in many new players and in need of new content because said topheavy players have had nothing more than Abyssea to do?
Streamline EXP (offer options besides leeching) and direct all resources towards the new level caps/content
The argument about starting at 99 is bunk, the game is sufficiently aged such that EXP to the level cap should not be a chore. Making Campaign a lowbie EXP playground in addition to raising EXP rewards in daily BCNMs along with raising exp/kill and FOV offer options for new players (few as they may) to quickly get to cap and enjoy the rest of the high level content the game is so deeply founded in.