I will explain this by way of an example:

If I want to know why (one instance of) quiz_statistics\task\recalculate is slow, I go to the task logs and I see:

This is not very helpful.

In fact, this task always runs for a particular quiz, and ->customdata contains $quizid. Since get_name is an instance method, there is no issue with making get_name return "Recalculate question statistics for quiz id 1234", and I imagine most other tasks are similar.

This would be such a big win for admins, that I don't just want to fix this one task. I want to make it a policy. (Because current practice in core is to have un-helpful names for all ad-hoc tasks.)