A lot of it is innate conservatism I think.
The certified GA world tend to be very reluctant to adopt innovations - automatic mixture control, additional engine instrumentation, electronic engine monitoring, coolant based carb-wrap are all pretty common in permit / experimental aeroplanes, but the certified fleet are all still sadly flying with what are basically 1950s American car engines.
Part of that is nervousness of stuff they don't understand, a lot of it is fear of the cost and complexity of getting approval on any changes.
G