For me the whole UI is reacting on state changes, icon, icon colors, state text, state values, … For those who want to react on the “same” 
state changes voluntary (as it is no must) to color or do something else, it would not be that much overhead. And not more than creating a template sensor, which is updating as well and use this one in the UI instead for having e.g. another value displayed.
I understand being defensive here. But perhaps with some limitations and as a starting point it would be still a good idea and as least some have voted as well. Thought that is more like a idea gathering and not directly augmenting down ideas. 