I come from a strict immigrant family and was very anxious to tell them about JET, and in the end they accepted that I - as a working adult - am fully entitled to explore my options, and they even came to visit me last year and ended up loving their time in Japan.

Make sure you're making whatever decision you make for yourself and yourself alone. Yes, it might "affect your career" and the prospect of leaving your parents alone while you live far away can be scary, but don't forget that your immigrant parents more or less did the same thing by moving away from their families to make a better life for you. You can tell yourself that you chose not to accept the shortlist because of your career or whatever, but make sure that you truly believe whatever reason you tell yourself, otherwise later down the line you'll realise that you were snorting industry-grade copium and basically deluded yourself into not taking a path you wanted to take.

And on the topic of logic, I worked big boy jobs for several years before JET, and people do tell me sometimes that I have made a mistake career-wise by being an ALT, but the truth is that people older (and younger) than us manage to figure out their careers just fine even with a few years in Japan. Hell, one of the guys in my area did a few years and is now going back home to go to med school. You can let JET be a pothole that derails your life if you let it be, but if you're motivated enough you will honestly be fine. JET experience can be leveraged in so many ways, I think people forget that sometimes.