Currently the workflow comments are a simple text field, having RTF for those comments would allow more descriptive comments to be created.
Additionally, it would great to be able to start a comments thread for collaborative purposes, on a particular Tridion item e.g. component, page, bundle etc... This would allow for more ad-hoc collaboration within a workflow activity or even completely without workflow. Something close to Tridion Docs Draft Space / Review Space commenting feature.
Alternatively or additionally, integrations / connectors for Slack, MS Teams or Jira would help to start and track a conversation about a particular component/page.