In small companies, people often fill multiple rolls. Our dev lead happens to be our lead UI designer as well -- but we all provide feedback. Sticking him on part-time tech support duty was a creative way of both giving us another tier of support while simultaneously forcing him to deal with our regular 'ol user.

Experiencing the mind of the typical user day after day has caused some major changes in his UI design philosophy. Don't bury things in menus, limit the number of ways you can do something, walk users through set procedures, etc.

There's a bunch of different approaches to interface design and many of them don't work well. We've all seen the beautiful but hard to use designs made by professional designers, and the control-panel-of-a-spaceship design made by developers.

It seems that what both cases miss out on is spending time working with and understanding the average guy on the street. Or rather, good interface design means spending lots of time optimizing for regular users.

What are you implying? That development leads should not or could not contribute to designing a good UI?