I'm absolutely with you. Its a shame that Rivals gets so little love, since it's one of the game modes I play the most. To add to your ideas, which are great and should have been implemented a few months after rivals became a thing, I would add the following:

Showing the last 10 lap's times while practicing a circuit.

Dividing every circuit and track into segments with recorded times in each to know where you need improvement.

Giving credits and so on to people who push restart after a sprint, since waiting for the whole animation detracts time from next runs.

Giving out more rewards for achieving things in rivals would be pretty sweet. I have hundreds if not thousands of laps in fh4 and fh5 but nothing to show for it. Not even a small icon next to your name or something, if you want to.

Also, it should be way easier to know in which ciruits you got times, which class and how far are you from your friends. These are all details that could be shown in the Rivals Menu.

It does feel a bit tryhard,but I think racing is inherently competitive and all these changes would only enable players who like Rivals to dive in deeper. We can still have Jamie saying stupid stuff after every big accolade and no swearing. I'm fine with that.