I don't know about you, but I am usually within a pretty “Yay WordPress!” bubble. It's a goal of mine to branch out more and see what I can learn from other systems, and perhaps use what I learn to make it easier for my clients to do things in WordPress. This thread, where people identify CMSs they like, isn't overly abounding with love for WordPress.
Granted, because of the medium, it's probably a tech-savvy audience that likes to tinker with new things… but still. Go read it and see the pain points people have with WordPress. And maybe even try some of the services mentioned. If we only look inside WordPress for potential improvements, the outside competition might just pass us by.
Oh, and as I'm sure you can guess: the main critique for WordPress is that managing it isn't simple enough. Here's a shameless plug for an article I wrote recently addressing the road to a simpler dashboard.