There are many ways in which student ratings cause controversy
Seldom do those who collect such ratings do not subject their planning, delivery or data analysis to the same rigorous critiques which might be applied to research survey data, yet too often the "findings" are appropriated to measure or manage teachers, or to shape and revise the curriculum.
This area needs a lot if thought, and is worthy of greater, more considered, discussion. As ever our reliable commentator at Tomorrow's Professor, is waiting in the wings to point to some insights.