@Winterthorn: If you give elves all kind of racial abilities, you risk giving them too many abilities that never actually come up. And those are bad design. The ideal ability is one that is relevant as often as possible, yet still isn't broken.
Also, contrary to what designers may want you to believe, ECL doesn't work. Maybe sometimes for warrior characters, if the race doesn't have any particularily problematic ability, but otherwise, LA just sucks. Especially for casters. Which are very common among elves. Also, people hate racial limits. You won't get much support for reintroducing them.
You are right that there is currently some disconnect, elves have that huge difference to humans in their life expectancy, yet 3E lacks the rules and flavor to make it work (that 2E arguably had to a greater extent). But given that the 2E rules very extremely unpopular, and everyone rejoiced when level limits got the axe (and elves stopped sailing away, but I'm not as sure of the reactions), I think just cutting the elf life expectancy is the easier way out.
For the purpose of this thread (well, being able to decently reply), I actually just re-read all the racial entries in the Races of Eberron and Races of Faerun books.
And what I found out was thus:
In Eberron, most of the elves are NOT reclusive and do NOT spend most of their time singing and jumping around. There is one reclusive elven nation, but also one that is very aggressive and expansionist. Most of the other elves, making up about 8% of the entire population of most "human" nations are explicitly mostly defined by the values by their nations and explicitly have much more in common with the humans of those nations than with other elves.
In the Forgotten Realms, the issue is less severe. In Races of Faerun, there even is a paragraph asking what elves would accomplish if they had human zeal. Nevertheless, it is explicitly stated that moon elves, the most numerous elf subrace outside of Evermeet, are just as likely to live among humans as among elves. There even is a notable example in the Silver Marshes.
Sun Elves are sufficiently reclusive, but then it is explicitly stated that they are not lazy at all, but study very hard. Though, similar to the point raised in this thread, they are described as perfectionists, so it is imagineable that sun elf wizards will research less effectively than his human counterpart. Their wizards still have four hours per day, +2 intelligence and a few hundred years over their human colleagues, but then the Forgotten Realms are so ridiculosly high magic that any decent wizard makes himself immortal anyway.
Wood Elves and Wild Elves are very reclusive, so they should be unproblematic.
So my beef is mainly with Forgotten Realms moon elves (the iconic elves) and practially all Eberron elves. Those live very similar and very close to humans in all ways, except that they live way, way longer. And somehow it makes no difference at all. Which doesn't make any sense no matter how you slice or look at it. The settings don't even address it.
Oh, I think it serves its purpose. The whole 'long view' thing is part of what distinguishes them (the Galadriel-esque wood-dwellers, at least).
The FR has been moving away from Tolkien elves and the Eberron did something completely different. So the elves of D&D's two main settings already don't have much of the flavor that has been described throughout this thread anymore.
And without that flavor, the life expectancy becomes very problematic. If your elf tries to accomplish as much as a human does (and modern elves do) and is not all that rare anymore (about 10% of the population in Eberron, increasing population in the FR), then they either need to live not much longer than humans (about 200 years sounds good), or you need a lot of suspension of disbelief.
Actually, I figure the city elves have even MORE reason to live that way. After all, there's a lot of money to be made selling entertainment, drugs, and sex to humans! I see elven neighborhoods in human cities as similar to Haight-Ashbury during the Summer of Love. And I also see human clerics condemning the elves as examples of laziness and immorality.
Not bad. But then all your elves need to be part of the entertainment industry (otherwise they would need to get an actual job sooner or later). I don't know if you really want all your elves in a setting stereotyped that heavily, but the idea has much potential if you apply it to a single town or so.