people hate ubuntu because it's actually a decent OS, and is gaining popularity.
this encroaches upon their "secret linux club", robbing them of their feel of superiority because most people can't be bothered to jump through the hoops it takes to set up older, shittier distributions of linux.
also, it uses GNOME. torvolds, their lord and savior, doesn't like GNOME because he can't readily fuck with the right click menu, so he is trying to herd everyone over to KDE.