The haters, they just keep hating. When was the last time you used these apps?
Been using KDE for years and years because I detest GNOME (though I say this and also happen to be wearing a Ximian shwag t-shirt, so go figure). Got a new machine at work a few months back, threw Kubuntu 11.10 on it. Woof.
This machine isn't a speed daemon but within 10-14 days all 10GB of RAM were used. Switching to another window resulted in 5-10 seconds of swapping and HDD light activity. And I'm only running a web browser, an IDE, a mail client, and Konsole. I could partially mitigate the issue by closing everything and logging out, but that would only reclaim a bit of memory. Rebooting was the only solution, and only then it just bought another few weeks until I had to shut down again.
Wiped it, installed Xubuntu and there's no reason for me not to use Xfce since I've been up for months now without an issue.
I'm not a "hater", but I don't know that I'll be a KDE user again. All I need is a workstation desktop environment. Not a tablet thing, not a phone thing, no "social media" tie-ins, just a stable, usable, reasonably svelte DE. Xfce has so far fit the bill perfectly.