> GNOME 3 is a perfect, and very recent, example of what you're describing.

Agree, in a sense that it has abandoned tinkerers and focused on mainstream users. I'm not sure the result is disastrous, though. In Google Trends GNOME has maintained its position relative to KDE:

https://www.google.com/trends/explore?q=gnome+kde#q=gnome%2C...

If you have more relevant stats, please share!