You might get lucky. Maybe the place you work is starting out with JSP 2.0, and can use Tag Files and SimpleTag handlers from the start.
That could happen.
But it probably won’t. Chances are, you’re working (or will work in the future) somewhere that’s been using JSPs since the pre-2.0 days, using the Classic tag model for writing custom tag handlers.
You probably need to at least be able to read the source code for a Classic tag handler. You might be called on to maintain or refactor a Classic tag handler class.
But even if you don’t ever have to read or write a Classic tag handler, they’re still covered (very lightly) by one of the exam objectives. Be grateful—on the previous version of the exam you might have seen at least seven or eight Classic tag handler questions on the exam. Today, exam candidates will see only a couple of questions on Classic tag handlers.