IMO, there are three categories of players in FFXIV:
1. Those who absolutely love the game
2. Those who learn to tolerate the games mechanics and stick around for personal reasons
3. Those who hate the game and leave

In answer to your question; No, the game play doesn't really get any 'better' or 'different' at later levels. The MSQ for HW is better than ARR (personal opinion ).
I just started the SB MSQ, so I have no opinion on how well written it is. You will always be required to participate in random que dungeons to advance the MSQ. If you play a tank or healer your wait times are significantly less ( the game is glutted with DPS jobs).
Not trying to discourage you, just stating things as I have experienced them.