Main reason to using package with Ionic is much more complex and sophisticated UI.
Can you imagine such modal from example above (with 3d transition and perspective and touchmove gesture) created with Ionic modal sheet ?!
Other types of pane such as horizontal, z-stack, and of course, presented from top inverse panes.
But for my projects, personally is the bullet-in case with fitHeight option. Content will be adjusted and automatically wrapped to the pane without additional workaround.
Also, Good cases to using panes in project without Ionic framework, whereas modal sheet not provided by UI components.