I don't Blizzard dares to change the entire engine of the game because it might alienate people with a basic system running it at the lowest graphic setting who don't want to buy an entirely new system just to play one game.

A new engine always comes with consequences. That said, the changing of vanilla wow could usher in a new engine easier than having to still support it. SoE tried to change out the whole engine, and failed miserably at it. Blizz has been steadily increasing the poly count in the world and on the player armor for years now (look at vanilla armor vs the greens in Northrend) and upping the quality of the base player models is hopefully in the works as well. In the original beta and stress test the poly count for the players, along with animations, were MUCH higher than in release. I believe they reduced the poly count and texture details in release to support more systems.

As you stated, the engine has done well for Blizz for years, and honestly the engine is the paper of the story. Just like replacing the paper with a higher quality variety doesn't add to the content of a book but may subtract, just having a higher quality graphics engine doesn't automatically add to the content experience but may make it a lot more difficult. Honestly I have an easier time with the suspension of disbelief when the content is a little less detailed, personally.

Where the hell do you get "10 year old engine" ?

Are you one of the people who think because the game started development in 2000 that that makes the engine 10 years old? The engine wasn't finished then. You don't date an engine to the moment work was started on it. When they first started working on the idea. the game originally ran on the WarCraft 3 engine. They realized that couldn't do what they wanted, so they scrapped it, and started working on a new engine. When you see video from 2001 of early gameplay footage, the engine wasn't even complete.

And you also don't just replace an engine in a game. That would mean reworking everything. That would takes years. You want to wait almost as long as the original game's development for an expansion pack? You know one of the reasons Duke Nukem Forever never got released? Because they kept switching the engine. It started out on the Quake 2 engine. Then swiched to the Unreal engine when it came out. Then the Unreal Tournament engine, then, altho unannouced but I believe so, switched to the Unreal Tournament 2004 engine, then finally stopped at the Unreal Tournament 3 engine, I believe. Each time they switched, they had to completely redo everything (technically, they didn't have to redo everything each time, but they were trying to be perfectionists). They weren't happy just using a damn engine, they had to keep switching to the latest and greatest, and it kept pushing the game back.

In addition to what other people have said about the engine, I want to point out that although I can appreciate the desire for pretty, it's not what I play WoW for -- and if they were to upgrade to a higher end engine (like the one in Aion, for example), I would have to stop playing.

I was able to play WoW reasonably capably (outside 25-man raiding) on an Intel GMA 950 chipset. I've upgraded since (for other reasons), but I'm still below the minimum requirements for something like Aion, despite having a brand new computer. (I did demo Aion once; it wasn't just a 'requirements on the box' thing, it really was unplayable.)

I'm pretty sure that Blizzard is pretty aware of the computers that their 11 million subscribers (or insert any number of millions you want) are using, and is making sure the game continues to be playable for the majority of them. Gradual upgrades to poly counts are the way they're approaching it, and I think it's working well.

My desire for a new engine is based largely on the very successful update that EVE Online performed about a year ago, which, AFAIK, did not take "years".

And no, I am not one of these folks that thinks a new engine solves all the problems. IMO, a newer engine is more standard in it's design(IE it supports all the various formats of data the art might take) would make use of newer methods of handling the data in memory and could quite possibly improve the performance on lower end machines.

Also, as was said before, the engine is the paper the story is written on, simply changing to a new one doesn't fix itself necessarily. But it does open up pathways that are simply unavailable now.

An engine overhaul and complete replacement are two different things. And forgive me, but a game that consists of mostly empty space and asteroids isn't exactly the hardest thing to upgrade. You can upgrade the individual models and achieve a good effect.

Sony upgraded the original EverQuest, but they didn't replace the engine. Neither did they do so with EVE Online.

@Brian

"Honestly I have an easier time with the suspension of disbelief when the content is a little less detailed, personally."

I agree. I actually like the cartoonishness of Warcraft as compared to more "realistic" games like Warhammer. I credit the uncanny valley.

http://en.wikipedia.org/wiki/Uncanny_valley

My favorite quote from the wikipedia page:

". . . a robot stuck inside the uncanny valley is no longer being judged by the standards of a robot doing a passable job at pretending to be human, but is instead being judged by the standards of a human doing a terrible job at acting like a normal person. "

The game actually does need an engine overhaul. Performance these days is really bad in a lot of areas (Onyxia with a lot of whelps up, for example, most of my guild can't do the Many Whelps achievement because it makes the game totally unplayable).

They could do that without scrapping it and starting over, though.