Thank you very much for posting your feedback. At this time, we will not be adding this request to the near-term backlog, as we are focused on other priorities. However, we re-evaluate requests every quarter and will reach out if priorities change. Please keep the feedback coming as it is critical for our longer-term planning.
With Sharepoint Online connector, the availability of Connector/Actions helps the hassles on getting the Access Token for the Web Service call, and/or helps the need to know how to call the REST API with complex body content to provide.
Availability of Microsoft Graph API will help the same, with Microsoft Graph Connector and Actions.
Optionally, a different version of "call a web service" actions with options of selecting a "Connection" to use in the "call a web service action" will minimize the efforts to have every single endpoint built as a workflow action in Nintex Workflow Cloud.