All of the answers posted so far are good but I'm not seeing 1 big glaring issue people are missing.
It's a privilege to work on New Code. If your just starting out or are new at a company or are doing freelance or maintenance - your probably not going to be writing new code or new sites. There are always bugs to fix; new features to implement on old websites or changes to existing websites.
JQuery for all of it's faults it may have (I still like it and use it when needed) is like Wordpress. It accounts for a very decent chunk of the internet. So in all likely hood, you'll come across existing JQuery code / sites and will need to work with them.
Should you learn it? Why not? It's not terribly hard to get a hang of and it's just another line item on your resume that someone else might not have.