@ StillLife
If you don't understand why people like certain games, that's fine...I don't understand why some people like brie or fish eggs. But I don't tell them what they 'should' like instead, or that they don't understand the art of culinary pleasure...
The same people who like Diabloish games can also often be fans of things like Baldurs Gate types and table-gaming, I've met many who love all three, because they find all three fun in different ways, whatever those ways are for them. I am quite positive that any of those people I've met - some of them who've been table-top gaming before video games were even really around - would be very offended by the notion that they don't understand that 'gameplay should move on,' or whatever, simply because they happen to (still) enjoy one particular game/genre.
There are many very old (non-video) games that are all very simple and repetive games rules-wise that are still hugely popular and widely played. Just because time marches on people aren't going to stop liking or wanting certain genres/stuff, assuming they still personally enjoy them.
To quote from Star Trek's Shore Leave (groan away...) perhaps sometimes, for some of us, "The more complex the mind (or work/living environment), the greater the need for the simplicity of play."