Completely agree. I once worked at a bespoke software shop where they had 'proper' developers upstairs, and support developers downstairs. (Quotes used to indicate how that made the support staff downstairs feel).

Most projects taken on by the company followed the same path: upstairs developers would code up the application as per functional spec, client would do a bit of UAT, accept it, publish it live, at which point the project was assigned to the support staff.

What generally happened next was the application would begin to fail on non-functional fronts, generally appalling performance and scalability problems.

Since there was minimal communication between floors (afterall, what could a 'proper' developer learn from a lowly support developer?), the pattern repeated again and again.

I'm sure that either rotating the positions, or having individuals responsible for staying with each application throughout its life, or some other form of mixing, would have drastically improved both morale and quality of apps produced.