I think it's dangerous to assume that because you can land a job as a software developer, you know enough about CS or can learn all about other areas of CS on your own.
There's a lot more to CS than software engineering. And a lot more to software engineering than application development.
Software engineering wasn't recognized as a field of study when I was in school, as a matter of fact I don't think software engineering is an ABAT accredited field of study anywhere in the same vein as, say Computer Engineering, for instance.
A wise man once said computer science is no more about computers than astronomy is about telescopes.
There's a lot more to CS than software engineering. And a lot more to software engineering than application development.