It seems that I have the same age as Jeff Atwood, but somehow not, when I read his latest post. Somehow I feel "been there, done that", because I would almost have agreed with him 10 years ago, while still being a freelance programmer, helping out in various programming teams. However, today I'd definitely say that maintainability is much more important than most programmers want to acknowledge.
Most programmers spend most of their time maintaining code, not writing new code. They may spend time on maintaining their own code - but it's still about maintenance. And actually, they spend much more time per SLOC when doing maintenance, than when writing new code. In other words, in order to be really productive, it's the maintenance part that needs to be optimized, unless you're doing a quick and dirty application that nobody is going to use (yeah, right!). The perfect source code is when it works perfectly AND cannot be easier to maintain. This includes simplicity, of course, but it also includes comments, understandable variable names, well defined context and well defined invariants.