I asked about that recently in another thread. Besides the argument that you can just make the panels bigger, the dust is also statically charged so it is sticky, and wiping it off is not easy. It is also amusing that we, as programmers, are inclined to suggest adding MOVING PARTS to a system that is not servicable, and that the same problem can be solved just by adding more of an already proven solution. It sounds like this one clever special mitigation that solves a minor problem, but instead brings the system down.