Users are Terrible Designers. Usually

In general, end users are terrible at UX design. For the same reason most of the world is bad at reading hieroglyphics. They are not trained in it.  So don’t treat them like they can design in the design process. Treat them like they can illuminate their requirements instead.

Other things to keep in mind:

• They can still – as can anyone – come up with a good or even great design idea. Because a good idea is independent of organizing and structuring the experience as a whole; and that’s the designer’s job.
• When you are doing a “co-design” session, it is about user requirements and ideas. Not solutions (except in highly simplistic instances).
• While users can’t design, they are the only ones, of course, who truly understand their needs. Focus your methods and energy on that aspect of understanding with them.
• Users will, given the chance, quite literally design what they hate (put every bit of content or functionality on one page for example). This was a common occurrence 30 years ago when some designers still believed it was a good idea to defer design to users.
• Don’t be swayed by the argument that users are smart. It is not relevant. They could literally be rocket scientists and brain surgeons, and it’s still unlikely they can design.