If you're view these systems as having a particular design, you're missing the point. They're meant to be abstract building blocks that are easy to consistently customize, which makes them a good starting point for your design system/pattern library.

Using the default look is totally cool for prototyping or building things where the visual identity isn't very important, but saying that their design is outdated doesn't make sense. If you want a particular design, you can always go to a marketplace like themeforest and get one that will suit you.