That would be a sad indictment on the state of Debian since it is not that easy to install KDE.
By the way the Debian installer has been flawed and buggy for years but Debian always insisted on releasing it with bugs.
Originally posted by http://www.debian.org/devel/debian-installer/
Synaptic is not included in the default KDE install because it's a GTK application. With KDE you get Adept and Kpackage (not to mention aptitude itself). You're perfectly welcome to run "aptitude install synaptic" if you so choose. Just like you're perfectly welcome to install KDE4 RIGHT NOW out of experimental. If you did you wouldn't be complaining about KDE4 not being included in Lenny because - perish the thought - it's just not ready yet, and it wasn't ready in time for Lenny's release schedule.
there is no bias against KDE.
Pretty much everything is SID has bugs. They also call it UNSTABLE eh. When those bugs have been wittled down to the point where a package meets the release criteria, and has lived in SID for 10 days in that state, it gets moved into testing. Every so often, testing becomes the next Debian stable (with ZERO bugs for every package being the criteria for stable IIRC). KDE4 simply doesn't currently meet the criteria for a Debian stable release.