In some cases it is needed that completed task would not be crossed out, but Obsidian do this by default when you click checkbox.
Proposed solution
Since Obsidian supports non-crossed task, it’ll be helpful to give a some choice between types of the completed task. For example, with Ctrl+click it turns [ ] into the [v] instead of [x]
It’s not native but the Tasks plugin supports cycling through different statuses for a given task type, and I do believe there is another plugin too, which I can’t remember the name of, which provides this kind of functionality.