Low information density means "less clutter" for somebody new to the interface, but it means "many more steps" to provide all the information that a dense design allows for. So much design fails to take into account human expertise, and our ability to learn complex interfaces. They get the A/B treatment which optimizes for beginners, which always leans towards the simpler, easier design.

This is why we'll never get a better spreadsheet design. In the hands of experts it's already perfect.

If modern UI designers were responsible for building musical instruments, there would be a lot more kazoos and recorders, and a lot fewer cellos and bassoons.