[QML]

I think it’s because data science has a more immediate, broader applicability than computer science. Not everybody needs to know how to program a full application; but they should be able to load in a dataset and statistically analyze it. Looking at the type of people taking Data 8 compared to CS61A (the introductory programming course), I would say the former is a fairly diverse crowd (political science majors, economics majors, biology majors, etc.)

It is also a possibility that Data Science is an easier topic to learn than Computer Science, and thus more popular.

[itronitron]

It might be more popular as many data science courses use Python and therefore students don't have to get their code to compile.

Seriously though, I think people are drawn to data science out of a desire to create stories with some underlying support (data/evidence) in order to influence policy or business decisions.

[Ar-Curunir]

61A also uses Python.