Microwaves are pretty terrible, and proof that wide consumer adoption does not really indicate quality or suggest that consumers adopt technology which _should_ exist.
So maybe it's not high on the list based on the value you are measuring but it definitely has a convenience value that isn't replaced by anything else.
The same thing happened with web search and social media. Now, those selfsame companies are trying to get us to adopt AI. Even if it somehow manages to fulfill its promise, it will only be for a time. Cost-cutting will degrade the service.
Like the remainder of the soup i made yesterday that I've put in a china bowl in the fridge. I was able to eat warm soup out of that bowl without requiring to make any other dishes dirty. Pretty convenient if you ask me.
Bonus: you can take a cherry tomato or a single grape and make a small plasma arc in the microwave. Pretty cool trick to impress and scare people at house parties.