There is also a secondary effect where more complex systems generate a bunch of surrounding materials: tutorials, videos, etc. It also creates job security for the people who learn it, as they have a necessary skill and responsibility in the company, as opposed to something that "just works" which doesn't require that.
Of course. If you were running an evil open-source company, you would favor "solutions" that generates demand for the services you sell (training, tech support contracts,...) while maintaining the belief that all this is necessary in "modern" IT.
I think it's Rich Hickey who links in his one of his talks complexity with entanglement through etymology. This entanglement is sometimes also there to bind the customer. Although more often the "never attribute to malice..." rule is at work, as it's just easier, cheaper, etc... to let the complexity grow.
