If you go look at any item database website, you can easily look up any mob in WoW or EQ2 and find out exactly what item could drop off said mob, especially raid bosses. Long before most people kill Illidan (if they ever do), they most likely have his loot table memorized, knowing exactly what he drops, and even the % chance he has to drop each item.
While it is still a rush to see what loot a boss has dropped, part of that thrill is no doubt gone knowing what each item is even before it drops. You know that Illidan has no chance of ever giving you ‘The Sword of Insta-pwn’. You know this because his loot table is static, and limited to only a few items. This applies to all boss mobs, and in general most mobs in a game that is item based, like WoW or EQ2.
Part of what makes EVE Online missions fun is collecting the wrecks once you have handled all the enemy ships in a given space. What makes this more fun, in some ways, to downing even a raid boss is that you never really know what you will find in a wreck. Most likely it will be a common fitting or ammo, which while useful are nothing really special. There is however always the chance that you will find some really nice named fitting, which will either be usable or that you can sell on the market for a decent amount of ISK. In some cases you might find something worth a large amount of ISK, which is what happened to me last weekend. During one of the level 4 missions we were running as a Corp, I looted a wreck and found a named sensor booster fitting. At the time I had no idea what it was worth, but when I went to put it up on the market the initial listing was 3.4 million ISK, and that was 20% below the regional average. I went ahead and listed it for 4 million, and within two days it sold. While I know 4 million ISK is not that much in a game that has 46 BILLION ISK ships flying around and getting blow up, but considering I had 23 million ISK at the time I sold the fitting, 4 million ISK was a big deal. The sensor booster dropped randomly; if we had run that same mission again it’s very likely I might not get anything near that value, but there is also a chance I get something even more valuable, or that I get a few fittings that improve my own ship.
I’m not saying this makes EVE Online better in every way compared to WoW/EQ type games (well, not in this post anyway, haha), but it’s another of those small things that enhances the game, increasing its appeal in the long term. Whether that design was intentional or simply a by-product of a game that is not item based I’m not sure, but I do know it works.