It is sad. Many Western people idealize Japan, and you can see here many comments saying that they keep working because it is their passion, when in truth they need to work because their pensions are terrible. I'm pretty sure that the 70+ years old ladies at the konbinis around my home and workplace are not there because it is their passion.

Would you rather they just disappear and die?

When people's dogs become older and inconvenient it is common for people to rationalize putting them "down" under the notion that it's some great benevolent act, instead of a selfish one. "Oh he couldn't jump on the bed any more so it was time to put him down". It's gross, but you nod and smile and pretend like they're being rational.

Similarly, many people want older people to disappear, and this is often masked in some benevolent "it's because I care so much" nonsense. People who want the elderly to disappear into some home somewhere where they can be sedated until they die. They can't jump up on the bed anymore, you see, so it's for the best. e.g. "I just want you to enjoy your retirement...best time of life...disappear"

A lot of older people want purpose in their life. They want to work. Particularly in Japan where there is an incredible pride and life purpose behind contributing and plying ones skills. I went down a rabbit hole of YouTube videos feature hole in the wall restaurants in Japan, and it was amazing how often it was quite elderly owners who would show up early and run the show, and it was clear they loved having it in their life.