Since I'm going to be sitting as a panel member on an MCA review board soon, I'd like to think I can, but apparently some researchers are having trouble...
Highly capable designers have an incentive to choose somewhat more difficult designs to better prove their talent, while less-capable designers have an incentive to choose highly difficult designs to obfuscate their lack of talent, Prof. Siemsen concludes.
Software Designers Strut Their Talent At Cost Of Profit, Says Study
This doesn't even get into the real reasons (Second System Syndrome™, Perfect System Syndrome™, Repeat Business Syndrome™, etc)... It seems to lay the blame at the feet of career concerns, but I'm not entirely sure that's the whole picture, especially when consultants get involved.
Irreducible complexity does exist, but if it seems Too Complicated™, it probably is, and you're probably Doing It Wrong™.
Great architects do The Right Thing™ for their companies or clients: a design that's as simple as possible, and no simpler.
Consultants: You'll never run out of repeat business from satisfied customers if you leave them with something that does what they need AND that they can maintain themselves. I always used to announce during project kick-off meetings, "I am leaving in X days/months/weeks. One of my goals is that you be able to absorb and maintain the deliverables that I'm leaving behind, so if it doesn't compute while we're working together, ASK me to explain it and WRITE down the answers so that you can retain the knowledge for your company."