My favorite part is the tooling. For example when you hover over a method name in VS 2019 it will show you its signature and what parameters it takes. If you right click on it and select "Go to definition" it will show you the code for the method. Just above the method name you'll a little chunk of text that says "2 References" which you can click on to see all of the places in your project where the method is invoked and links to review them. What makes ASP.NET fun is the quality and completeness of the tooling.
> Seems like companies that are not updating their apps is more common than those that do. I wonder why.
I'm guessing this is just a product of .NET being big in the "enterprise" world. I dont mind modern Java, but I remember when I was working with Java around Java 7 people would complain about being stuck maintaining Java 1.4-1.5 apps.