I'm not a usability dude, and following the usability mailinglist has taught me it's an art I shouldn't get too involved in. Unfortunately, while we have a few hard-working usability experts in KDE, they can't thoroughly check each and every application.
Luckily, we have users joining KDE from a platform known for a strong focus on usability. I'm not saying we should copy the approach others have chosen for usability. KDE is different and has different ideas about usability - enough has been said about that. However, advice never hurts - and there are several points in this blogpost that make sense. The contents have been discussed a bit on the usability mailinglist, and as I said - several points make sense, others might not. Yet Sebastian's blog might be helpful for somebody who wants to improve some obvious areas in KDE in terms of usability, so I thought it'd be good if ppl read it.
Personally I think such articles (I can hardly call it the usual blog) can help in improving KDE, as they point to issues and solutions developers might not have been aware off. Peter Penz (of Dolphin fame) has read it and implemented at least one suggestion, while several others were already done in KDE 4.3 branch. Who's next?