EQ2 got its latest expansion on Tuesday, which meant that, inevitably, it got its first characters to reach the new level cap (90) on Tuesday.
This isn't especially unique to EQ2, even if the time involved was unusually short (reportedly as low as three hours after the servers came up) due to some of the game's quirks. First off, there are seventy five slots in player quest logs, not counting collection quests. This allowed players to "bank" an unusually large amount of exp to redeem immediately on launch day. On top of that, there are a variety of experience bonuses (recruit a friend, paid exp potions, and unpaid veteran reward exp potions) that are fair game even on expansion launch day. All of these added up to some very quick leveling.
Personally, I picked up nearly half a level in an extended launch night session. Judging from past experience, I will probably hit level 90 in about a month and be "done" with the solo quests, tradeskills, and reputations for Lyriana in around two months (plus or minus depending on workload and how beefy LOTRO's Volume III patch ends up being). That would put this expansion approximately on par with the time I've spent on other recent AAA expansions (WoW's Wrath, and LOTRO's Moria expansion), before working on alts or serious "endgame" content.
How long should an expansion run?
Though a single month or two may seem short, even in the context of an expansion every year, it's worth remembering that this figure represents a month just to get from the old cap to the new one. If you're joining the game from scratch, as I did about a year ago, you've got far more time ahead of you before you get to the level ranges where most of the players are.
Where you could make an argument is for a slightly tougher experience curve at launch and reduced requirements as the expansion ages (especially if the next EQ2 expansion does not increase the level cap - the game has only been raising the cap every other expansion for a few years now). However, what purpose would that really serve?
Having the steepest experience requirements on launch day, which is typically when there will be the least content available, runs the risk of leaving players without enough to do. Indeed, SOE had to spend a significant amount of time this patch adding content to the 60's because that level range relied too heavily on group content that players can no longer count on being able to complete. Moreover, if you ultimately do opt to speed the leveling curve at a later date, your latecomers may actually end up at a disadvantage in terms of less time to obtain gear and cash before their next level.
At the end of the day, experience levels are an arbitrary number. What matters is whether the expansion provides players, of whatever level, with enough to do.