In the latest update, pit stops have been made more important. I think it would be a good idea to do the same with cooling and reliability because at the moment they have almost no effect on the gameplay.
How about having different strong points for each circuit type (street, fast/long straight sections, bendy, technical tracks, etc, etc), then you would need to take more reliability, than acceleration on a street circuit, for example. Or a fast track may need to have more concentration on cooling tham cornering, maybe.
If every track type were to have a different big 4-5 traits, even by just one from others, that would make development more interesting, in my opinion.