Why does the Solow Model matter for undergraduate students?
I disagree that:

a) The core curriculum should not include things that are relevant only for those pursuing graduate school.

b) A university degree should necessarily focus only on career outcomes for students.

c) There are only two relevant careers and therefore the only thing worth teaching is how to handle different types of data.

The core curriculum needs to provide a foundation for all future paths of students, which includes those going to graduate school.

Further, a university degree is foremost a scientific (or at times artistic) pursuit within a field and not a trade school. That is why professors are scientists (or at times artists) and not industry professionals. After a bachelor's degree a graduate should at least understand the basics of that field. Sure, many of those skills learned at university can partially be transferable to a job in the real world. However, that's a different story, which often does not involve the actual material learnt, but other skills learnt along the way, such as critical thinking and writing.

The Solow model is the foundation for beginning to understand economic growth and development. That is at the core of what the economics field aims to understand. Even  most policy debates will inevitably involve growing the economy or creating jobs. I would argue any student that is not interested in that question at all has no business studying economics. That is why the Solow model is in the core curriculum.

Lastly, there is a reason not everyone studies statistics and IT so that we can all become data analysts (for business or otherwise). The reason is that there are many other career paths.