Yeah and then they would lose those people able to run it. The engine is designed so everyone can access the game not people with huge budget PCs. WoW has never been about a realistic approach with it's graphics either. WoW has been accessible to people with low end pcs since 2004 when it could be run on a Pentium 3 and Windows 98/ME.
Windows® System 98/ME/2000/XP OS
800 MHz or higher CPU
256 MB or more of RAM
32 MB 3D graphics card with hardware transform and lighting, such as GeForce 2 or better
4 GB or more of available hard drive space
DirectX® 9.0c or above
A 56k or higher modem with an Internet connection
The original launch system requirements above.
https://us.battle.net/support/en/art...m-Requirements
Today's system requirements above. It's changed a lot over the years. Copy pasted the one from their Battle.net site because it would be a mess to copy it over.
In short WoW will never go the realistic or high end graphics approach because A- the games artstyle isn't that and B it's aimed at people with older spec machines. Great graphics don't always make a great game.