Only wanting to throw my two cents:
Here in my mind, I found that, "The journey is more important than the destination." I'm sure most of you have heard of this saying, and after getting to 50, it is actually quite true. I LOVED exping in 14. Endgame I feel like there is no more progression, and I feel lost. Not to mention not a lot of people seem to want DRG for their endgame events (people would then say level something else, but I wanted to play the game with my favorite classes of all time, even in endgame). The journey was the most fun I have had in this game. I was always competing with a close friend, or just giggling and laughing through deaths. But after all that, it feels like, what now? I did all the story quests I needed to do. I tried leveling other classes, but it just does not feel the same. Honestly, I like the leveling progression. I do not powerlevel or have anything to do with it, and I do not get into grinding parties. It wasn't fun before on other servers, and it won't be fun now now or in the future.
OP, I totally agree with you. I say do not make the leveling slower or faster, but throw in more challenges along the way (which they are planning to do anyway, so I'm happy).
I also do not care about overleveling for anything to the point that it makes a challenge too easy. I'm not in FFXIV for the endgame, I'm in it for the journey to that with my friends.