I agree that there should be at least some effort put into making the alt grind more exciting and interesting for people. It doesn't have to be loads, most people have high level characters and the endgame is a massive part of WoW. However, it makes sense to keep all levels of the game interesting. I dont want Azeroth to become like the starting continents of Everquest did, with huge empty zones where you were lucky to see another player at all, because everyone was over in Kunark, Velious or on Luclin. This is presumably something Blizzard recognises too, for instance their decision to keep Auction Houses out of Outland so that people had to return to their native cities.

This can be done in a number of ways. I think heroic or new expanded versions of low level dungeons would be awesome. Another way is to continue to revamp or open up new zones occsionally as was done with Dustwallow Marsh. I'd love to see Gilneas opened up to become a 30-40 zone, or perhaps for a new series of questlines introduced to the Barrens that detail the environmental changes that should be happening there as a result of the actions of your first toon.

It doesn't have to be much, as the majority of players are (I believe) are involed in the endgame. But some additions and reworking would certainly go a long way!