I am looking to be able to send Notifications/updates on Tasks to only the Task owner(s), not all members of the group, OR the ability to assign Tasks to non-members of the Plan.
For example. Supervisor has created a Plan of misc. tasks and created different Buckets for each admin in department. When I update Tasks in my Bucket, each admin Member of the Plan recieves Notifications that are not pertinant to them. Additionally, when I try to add individuals that I am working with to one of my Tasks, I am unable to do so if the Task is already assigned to me.

Additionally, it may be helpful as individuals update a task, to be give the option of whether or not a notification should be sent. As the "owner"/Member of the Plan, possibly creating an EOD, bulleted Notifications email, as opposed to an email notification for each update. For example, I may update one of my Tasks multiple times in a day, and update multiple Tasks; this can create upwards of 20 email notifications for my supervisor. Add seven more admins under a Plan, the notifications will overwhelm the supervisor.

Emails posted to the Group should be promotable to Plan/Bucket along with their attachments with appropriate metadata mapping, i.e Subject -> Task title etc. We can also establish conventions like @<user> on the subject would be mapped to Assignee etc

A similar facility is used quite extensively in Trello to accommodate integration scenarios with external apps but this Use Case is covered well in O365 with Connectors. The unique selling point of Groups is that are email-enabled therefore can act as a Queue/Routing Point for other actions, either manually (explicit UI actions) or automatic.
This would require the addition of extra APIs.

Provide a better way to allow integrating systems to detect changes within existing tasks or discover new tasks.

This can be simply achieved by:
1. Add a lastModifedDateTime attribute to the Planner Task, and
2. Add the ability to filter the list of tasks based on a supplied lastModifiedDateTime value.

This will need to be modified whenever any attribute within the Task aggregate is changed.

Other options (that would be helpful) include (1) providing a Version Number on the Task, or (2) Guid/Checksum that changes on every change. Whilst we couldn't meaningfully filter on these, we could at least use this for comparison purposes.

I am working on data integration for planner making API calls for reporting purposes.

I am surprised why this feature (Tasks Associated To User) has not been enabled, as rest are enabled in planner.

Everything below works when I am a Member of plan.
 Plans In Group
 Plan Buckets
 Plan Details
 Plan Tasks
 Task Details
 List Of Users
 Group Conversations…Etc

Then why not Tasks Associated To Users for the Plans which are shared can be extracted? It’s only working when I am the owner of that particular plan, and I don’t think one person can’t be listed as owner just for reporting purpose and also there is no option to list as an owner.

It makes sense when permissions are restricted to extract Tasks of a User in Outlook. I think planner tasks are entirely different, this doesn’t make any sense at all when rest all can be extracted when I am member of the planner and not Tasks of User.

I don’t think it’s even mentioned in Known issues of Microsoft Documentation as well, If I am right.
https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/api/planneruserlisttasks

I tried reaching out to Microsoft resource, even he was not able to help me out on it.

I suppose its just a small change from Microsoft end, but not sure why its not being enabled.