You might care if you can deliver the same functionality with a fraction of the complexity and better performance.
I care because if you're interacting with other developers while building that site, you might be leading credulous hype-followers down a path which means I end up having to maintain yet another pile of useless, overcomplicated JS.
The people paying you to make things probably are going to end up carrying about maintenance down the road; if you don't care, you are providing the kind of bad service that demonstrates the difference between much of what goes on in software development and actual professionalism -- a doctor it later that didn't concern themselves with, and proactively warn, a client/patient with that kind of down the road consequence would be guilty of professional malpractice.
You seem to think i'm advocating for sloppy and un-maintainable programming...
I'm advocating that the web is going to be the best platform for some applications. Users aren't going to want to go through complicated installs to install a program that they will only want to use a few times. They don't want to spend minutes or sometimes hours installing a program that they will only use every now and then. They want to be able to use the software from their iOS/android mobile device, computer, laptop, tablet, friend's computer, osx/window/linux/whogivesafuckOS. They want it to "install" in less than a second, and they want to be able to use it and leave. They want it to be secure, sandboxed, and know that it won't interfere with other programs they are running on their device. They want to know that it is in it's own sandbox, and they want it to be as easy as typing in an address or clicking a single link from a search engine.
If you know of any other platform (even a single other platform) where that amount of speed that the average person can install, use, and "uninstall" a program with the security, ease of use, and sandboxing of the web, then by all means please let me know.
But until then don't act like anyone writing software targeting the web as a platform is doing some kind of disservice to society. It's not. The people doing a disservice to society are people like you who "look down upon" those who develop for or use the web to get shit done.
Calling it "bad service" because you don't like how it's used is juvenile, and downright wrong.
"They want it to "install" in less than a second, and they want to be able to use it and leave. They want it to be secure, sandboxed, and know that it won't interfere with other programs they are running on their device. They want to know that it is in it's own sandbox, and they want it to be as easy as typing in an address or clicking a single link from a search engine."
I don't know why anyone would trust a web browser or app to do all that. They fail to every day due to enormous complexity. Sounds like you need a https link to a standalone exe that's written in portable, safe-by-default code utilizing only necessary OS API's. Like us non-Web types build things past and present. Interestingly, one of the old arguments was that even our micro-apps would be too large vs web pages. The web app, framework, and JS craze mean those are now bigger than many stand-alones. That's funny.
"They want to be able to use the software from their iOS/android mobile device, computer, laptop, tablet, friend's computer, osx/window/linux/whogivesafuckOS"
Only part that's tricky. Gotta compile the portable code into standalone for all the common OS's. Many tools to make that easy. Then, perhaps a page or JS that determines their platform then redirects to the right link. Problem solved.
Displaying some text and graphics on a browser with user's privileges is better than printing some text and graphics to a window in a process with little or no privileges? It wasn't better at any point in web development. There were simpler things at each point. Just not widespread adoption. ;)
I like to think that they've got real problems to solve though.