The leveling curve became a complete joke after they sped it up and i'm almost positive this was pre-launch. I specifically remember outleveling a major quest-hub area (i think the main quest hub in your late teens/twenties but don't remembver the name) while right in the middle of the questline and wondering how in the hell anyone could think that's a good idea.
Leveling curves always seem faster later, because they are. Information isn't as easy to get and powerful gear isn't as common and people are trying different things and actually exploring. Sure, there were a select few who had enough information to make a power-leveling plan, but aside from a few poopsockers with a plan to rush to max, the exp rate at launch seemed to feel good. It walked the fine line where people would say 'man, leveling is slower' but take it as a challenge instead of it being a complaint and seen as an unacceptable hindrance.
I think that line is what needs walked. We can't go back to head-against-wall progression. It has to be present so people notice and feel it working against them, so they dig in a little and push back. Whether 'kids these days' will respond well to such a game is a point of debate, but I think there have always been and will always be people looking for challenges in a game. I'd argue that increasingly challenging games and content is more popular than ever. It's just that other genres have found clever ways to continue ramping up complexity and challenge and the mmo market is so stagnant most of the players are even starting to believe the 'that would never work' bullshit that doesn't seem to plague other industries to the same extent.
Back to Vanguard, though, for some reason... I think you actually hit on one of the things that was wrong with the leveling curve: quest hubs. The exp rate wasn't the issue, but that quest hubs created a leveling curve that was. The game suffered from split philosophies. The first (original) philosophy of a huge world with dungeons and places to explore and a stiffer death penalty and slower travel all helped temper the speed of advancement. It was a system designed to be supported by quest lines, not quest hubs. Even today, if you play the game based on a quest-line experience and avoid the quest hub and local fetch quests, it's a totally different experience, and one I will claim is still pretty good.
The further problem isn't just that the quest-hub style gaming didn't fit the existing game design, but that it split the player base. If you were like me you were in Skawlra early on in launch getting your ass kicked, but being rewarded for it, and the game felt like a true EQ-style revolution. Over time quest-hubs were found to be 'more efficient' and the path of least resistance won out. There became less and less people to group/explore/dungeon-crawl with, and those wanting that group/explore/dungeon experience often didn't make it to the higher levels when quests were more likely to force you into dungeons. And the people who did make it via quest hubbing were either shitty at the game and got pissed off and left or didn't want a dungeon experience because that wasn't the game they had been given so far. The players didn't know what the game was supposed to be, because the game itself didn't even present a coherent image.
In beta the only thing more painful than seeing people in chat complaining the "don't know where to go" was watching Sigil actually start responding to those 'complaints' by making changes. Not a bad thing to point players in a direction or even lead them by the hand to a dungeon or start of an overland quest-line. But instead they started leading players to the quest hubs and the hundreds of quests they had shit out just so they could compare their number of quests with that of WoW. Many of the fast, easy, solo sort of arguments and systems weren't even bad in a vacuum, it's just they went against everything else the game was doing.
I guess the point is decide what the game will be and work on making it the best possible version of that game, instead of trying to make it some aborted version of every-game. The second things start getting tacked on for the sake of some 'other' audience or style, everyone loses, because the original target audience sees it as betrayal and the new audience realizes it's just bullshit pandering.
Damn Vanguard.