Hi there, thanks for raising this, it is something that I have been actively thinking about for a while now.
You are correct about the limited variation, but it’s not a limitation of the theming system. We have built a tonne of very different custom themes for hosted customers, there just doesn’t seem to be the same demand for them in the open source community.
It is something that we are aware of and have been discussing internally. Our design team are actively working on some different variations of themes and theme components for addition into the setup wizard. Keep your eyes out!