Make it so the Current Expac MSQ doesn't level you

[Gortys]

I would argue that people want to be engaged in the world, not necessarily with a single story. Take Tam-Tara Deepcroft Quest chain and subsequent hard mode quest chain, did you not find that engaging when you first did it. I agree being forced to repeat dungeons and grind them is not fun, I remember the Aurem Vale runs back to back to hit 50 back in ARR . Again, that's not what I'm suggesting. Have you everyplayer GW2? Each part of the map has it's own little storyline where you do objectives to fill hearts once filled they are filled. ESO does something similar with self contained story lines in points of interest that you go through, this would be a huge boost and a way of breaking up the MSQ which by it's nature is always going to be more cutscenes than it isn't. So have the MSQ be more to the point, with only the pertinent information dumped on the players for the plot and storyline, and then have the world tell the players the rest of the story of that country region etc etc.

I've played both ESO and GW2 quite a bit. GW2's hearts are like yellow quests and totally optional. I do dailies if I want to level in GW2 and even then the leveling is more horizontal at some point.
In ESO the zone quests are pretty much an MSQ. The old MSQ isn't even necessary and feels outdated. And again, there is a different leveling system in place in the game.

It's kind of hard to compare these games since their end game leveling is also different.

Edit: Also, you have been playing the game for quite a while. I have been playing for a while. We know tricks to level faster and many of us are doing fates and other content along the way. I've seen some stream and need to grind fates to catch up even in this expansion. It may not be the MSQ EXP that is the issue so much as the knowledge you have concerning leveling efficiency.