It's the same reason that cooking recipes often become overly complex. (A sprig of this and a pinch of that.)

We are often embarrassed by the simple.

The simple makes us feel small, unsophisticated, and unimportant.

I always find it amusing when I find a way to solve a problem simply, and my coworkers answer somewhat directly that it seems very simple.

To me that's mark of success, but to many it's uncomfortable.

Of course if we didn't work on it then it's over complicated it needs to be rewritten. Go figure.