I've never been fond of elves taking a constitution penalty in Dark Sun... Yes, they are lazy, but I have always felt the con penalty was an "easy out" for choosing a stat drop. Athasian elves aren't as frail as elves in other worlds... in fact, by this conversion, a player might be led to think that athasian elves are even more frail than other elves.
I'm not saying they should receive a bonus per se, only that the penalty should be placed on another stat. Charisma seems to be appropriate, for a couple reasons:
The elven philosophy of "keep up or be left behind" is not one of compassion. As a race of theives, looking out for others is a rather foreign idea to them; making friends for them is difficult.
Also, Elves are rather infamous. They are astute liars, but even then they have a hard time getting people to trust them. In their social encounters, making the other person think they are honest is a frequent hurdle they have to jump.
A penalty to charisma seems to be in order, but a bonus to bluff checks would also be appropriate. (not necessarily making up for their charisma penalty)
I am not entirely sure about the wisdom penalty either; It sort of plays against the idea that elves sometimes have to live by their wits. Im not saying they deserve a bonus, but a penalty feels inappropriate to me.