I agree with a lot of your points; ego is a dangerous thing. However, I think it's important to differentiate between the two major types of rewrites (or claims as to why something should be rewritten): 1) The code is obviously subpar vs. 2) the programmer doesn't understand the code.

I've had to deal with code written by 3rd parties where I doubted the person was actually a programmer who wrote it; nonsensical or nonexistent naming conventions, large methods of dubious logic that were often never actually called (anymore?), and a general avoidance of best practices (and I don't mean advanced code; even simple things like code comments along the lines of "this is a for loop").

#2 is a different beast altogether and I think this more applies to your last paragraph. Is the source code too advanced for the programmer reading it, or is the code/architecture too obtuse? Unfortunately, I think it's often primarily programmer laziness more so than the design itself. I've been told by devs they don't understand a system and when asked what they don't understand, they simply shrug their shoulders. If you don't make an attempt to "get" the current system, in no way should you be allowed to rewrite it from scratch. You need to at least learn the mistakes of the current system.