learn it if you like it/find it useful for you.
you can get along just fine without any japanese knowledge whatsoever in japan, but knowing the language has it’s perks, being literate is a step up in extension, and being able to write by hand is even further so an improvement. the step after this would then be calligraphy on the writing side, or dialects/classic japanese. see the progression here?
japan is a modern country. their native language makes learning english painful and slow, so they do value your every effort to learn japanese. they’re also happy to try out their english with you, but you going through learning japanese is highly valued.
while japanese people are proud of their culture, language and japan in general, they’re also a curious bunch who love the exotic.
with the olympics in less than 2 years, efforts are being made to make the country even more accessible for foreigners - which is the very opposite of “you need advanced skill x to live in japan”.
main problem in this thread is the usual: some people don’t have a clue, but everyone has an opinion. take everything you read here with a grain of salt.