Complexity is also introduced by well-meaning people on the implementation side as well. Software developers like challenges, and the challenge of building a complex system that serves up a simple interface is especially alluring. Consider DSLs, abstractions and the attraction to being the one to build a framework that gets leveraged for years. This drives us to introduce huge complexity debt we defend with statements like "it makes it so easy once you understand" and "it will save us so much coding." Writing the lines of code is rarely the big cost in engineering: it's the understanding, the communication and the maintenance.
Ok, but did it save so much coding, or not? I do try to restrain myself from being clever when I realize it's really not worth it, but being clever sometimes does pay off. Extra coding is complexity too.
That said, making a simple system that provides a simple interface to a complicated (or at least, a sophisticated) issue, is much better. And, you don't have to control your ego either. You can learn to take pride in the expressiveness and simplicity of your code.
Ok, but did it save so much coding, or not? I do try to restrain myself from being clever when I realize it's really not worth it, but being clever sometimes does pay off. Extra coding is complexity too.