While I agree that additional options for income would be a good thing. Many other metrics that you mention are too easy to game. Andrew Dacey already mentions the issue with views.

However, comments could easily trigger spam if there was a payment for these it would likely trigger a lot of “great story” comments that add no value to the experience.

Likewise, highlights again could be undertaken with no value add to the experience.

The entire idea of being paid in the Medium ecosystem is based around creating value. If you can create value then you can potentially earn payment. Therefore I believe that they changed the system from payment for claps to payment for read time because you could clap without ever reading the article.

A more valuable option I believe would give people the option to support their favorite writers beyond just reading. One option would be to buy credits that you could tip your favorite writer for a good article. It means that people would have options to support writers beyond just reading their article.