My feelings toward EPL and WPL are somewhat ambivalent. On the one hand the areas have a really cozy setting, with tons of lore and interesting quests, on the other hand you have this really gloomy and sad looking area with tons of extremely annoying mobs and quests that take forever. It might depend on the mood you're in. Or maybe it depends on what else there is to do? Considering we've got this Curse of Torpor thrown over us in the wait for Cataclysm, this could be the perfect time to seek out these areas, that will be completely changed when Cataclysm comes. Not only that, alot of the quests in EPL and WPL (and other old endgame areas of Vanilla) will have connections to quests in Cataclysm, which might make it worth to run them through one last time to know exactly what's happening when Cataclysm hits us. I usually feel an area or a quest is so much more fun to do when I know the whole story behind it so I can be more emotionally immersed with my actions. It's not just "kill 10 kobolds", it's making Auntie Petunia happy because her apples won't be stolen by those nasty Kobolds anylonger!
If you've just recently completed Loremaster or the Seeker, you might just have had your run-through of the EPL and WPL quests. If not, I seriously think you should consider taking a trip there in a close future. Take this chance to experience some of the oldies but goldies quests. Even if you were around back in Vanilla it might be worth doing them again (with another char though) just to freshen up on the story! Unless you hate questing and lore like like a napkin hates fire (in which case I feel sorry for you) you'll most likely have a really fun time. Since you can solo everything, if you're a level 80 char, you don't have to collect huge groups of people just to be able to complete one part of some quest chain, but can experience everything in your own pace. It is also a good opportunity to take a char within the proper level range 55-65 to do it, instead of the same old grind in Hellfire Peninsula (this is what I am doing). Most quests have been nerfed (mobs that used to be elite aren't anylonger, for example) and you should be able to solo most things anyway.
There are several good reasons to do this;
What's up with the Redpath family? There are many interesting quest chains in EPL, and many of them are about the Redpath. When questing in EPL you also stumble across many of them, some of them dead and some alive. The entire family consists of Joseph (dead), Jessica, Pamela (dead), Carlin, Marlene (dead) and Marcus (he's in Southshore however). Situated at various places across EPL, all of these Redpaths give quests, which all come together to help you puzzle together what happened to the family and thus to Azeroth some years before you were brought into the game. Through this family we get to learn how the scourge plagued the land and turned it into what it is today, the very foundation of every subsequent major event in the storyline of WoW thus far. Following the entire story, talking to each member of the Redpaths and puzzling it all together is a rather epic experience, with many fun and interesting quests along the way.
Another person we constantly stumble across on our adventures in Azeroth is Tirion Fordring. He too can be found in EPL, giving the player an opportunity to get a little closer to understanding this man. Considering what an important role he later plays in Icecrown Citadel, this could well be worth checking out. One of his quest chains includes finding out more about his son Taelan Fordring, Highlord of the Scarlet Crusade (dun dun duuuun!).
If you have any kind of gathering profession, like mining, herbalism or skinning, questing some in WPL and EPL could turn out to be extremely profitable. On most servers I've played on endgame herbs, ore and skins gathered in these areas easily sell for 3-4g each (yes each!!).
Even if you don't have any gathering profession you'll get plenty of nice stuff to sell from all the mobs you'll be killing, most importantly various types of meat which usually also sell like water in a desert.
The Cauldron quests in WPL are apparently some sort of war effort to take back WPL from the scourge. Kinda like what we did on Isle of Quel'danas in BC. This doesn't seem to be completed however, I wonder if this will somehow be re-implemented in Cataclysm?
Some of the funniest and most interesting gear pieces, especially trinkets, can be acquired through some EPL and WPL quests. One of my favorite is the Barov Peasant Caller! It will summon three servant that helps you fight, cook and clean. Practically useless of course, and all the more awesome for that.
And all these are just some of the reasons you should give EPL and WPL a run-through!
WPL and EPL might not look so pretty at a first glance, and probably not at a second glance either. But hidden underneath all those gloomy trees and annoying mobs are some of the most interesting quest chains in the game, especially now that they might actually turn out to be important for soon-to-happen events. I really recommend you go check them out if you want something to do, and you'll most likely have some hours of fun!
Bonus tip: Listen to music from Diablo and Diablo 2 while questing to really set the proper mood!