Hmm, I am no expert on WoW, but after six years of Diablo II I can agree that simplistic yet addictive games brin in the masses. Diablo II is nothing more than a glorified side-scroll shooter. Argue all you want, but in the end that's all that remains. And it was popular like nothing before it.

World of Warcraft builds on the reputation Blizzard has as a game-designer. I dont know if its good or bad, but all those people dont just play the game because they want dumbass games.

No they dont play games because they want "dumbass" games and nothing else, they probably play them because Blizzard makes good, solid games wich are action oriented and easy to get into for casual gamers.
However none of Blizzards games have any significant depth or complexity, including WoW, and that is also one of the reason why their games are so succesful.

WoW does not offer any new revolutionary game concepts or mechanics. It's a simplistic, easy played MMORPG with absolutely no complexity whatsoever. However it caters to the casual gamers as the leveling threadmill is linear and easy to follow which means that anyone can make it to the level cap with minimum effort (except time investment), compared to other MMORPGs. Also everything from crafting to fighting in WoW is so simple a child could do it.

And if a child can do it, then the game is dumbed down. WoW has literally houndreds of kids in their lower teens running around with capped characters and decked out in the best armor. As a comparison how many kids in their lower teens you think would be able to beat this game on tough difficulty?

i played SE III and IV, haven't cared to touch V yet (might never).

one thing i'd add to some of the comments thus far is this. the entire focus of SE is combat. GC2 (both DL and DA) is a 4X game in a truer sense, IMO, becaue there are multiple victory options and a fair amount of development that's gone into each of them.

also, some of the above people have suggested that there are more options in SE-V, but if it's like the previous two incarnations, i find they're variations on a limited theme: killing. sometimes i felt like it plays almost more like an RTS.

in GC2, the "simplicity" has a paradoxic affect of making small random events mean a lot. in one game i played, i'd colonized about 15 planets. one of them had pirates in orbit, and i set up a relationship with them. it was a class 26 planet, and has a 50% starship bonus. that means all the ships that planet produces had 50% stronger offense and defense scores. it was huge, in some respects. i managed to nab another plaent, class 18, with a 55% research bonus. i had my industrial and research capitals - but that doesn't happen every game.

i think in GC2, it's all about capitalizing on small advantages. i just got lucky (very lucky) that time. another time, my starting planet had two influence bonuses, so i fouced on colonizing planets farther away because i knew i'd be able to influence nearer ones into joining my empire. you can stick to a formula that works for you in GC2, but i personally have a lot more fun experimenting: something vastly enhanced by GC's unparalleled mod-ability.