It’s about 5 times longer than previous releases were maintained for, and is an experiment. If there’s a need for a longer term support branch, there will be one. It’s pointless to start maintaining an 5+ year branch with 0 users and a handful of volunteers, none of whom are paid for doing the maintenance.
So yes, in that context, 15 months is long.
A lot of people do. Especially on GitHub, where you can just browse a random repository, find a file you want to change, hit the edit button, and edit it right there in the browser (it does the forking for you behind the scenes). For people unfamiliar with git, that’s huge.
It’s also a great boon when you don’t want to clone the repo locally! For example, when I’m on a slow, metered connection, I have no desire to spend 10+ minutes (and half of my data cap) for a repo to clone, just so I can fix a typo. With the web editor, I can accomplish the same thing with very little network traffic, in about 1 minute.
While normally I prefer the comfort of my Emacs, there are situations where a workflow that happens entirely in the browser is simply more practical.
Building a browser engine is hard, especially when the target is moving at a rapid pace, and that target is controlled by Google. Like it or not, the web as it is today, is pretty much driven by Google (and to a lesser extent by Apple and Microsoft) these days. They can throw infinite resources into developing the browser engine and the browser itself. The closest competitor we have today is likely Servo, and they scrape by on pennies.
Developing something from scratch, with even less funding and expertise than Servo is a non-starter. It’s not going to happen. Sure, sure, there’s LadyBird and some other independent efforts, but I very highly doubt they’ll ever catch up to the three major engines.
To develop and maintain a browser, you need people, and they need to be paid. Paying open source developers is… quite a big problem in and of itself, even for things considerably easier and smaller in scale than a web browser.
They would not, because for every developer who would do this, there’s 100 who would not, because their livelihood depends on people with Google browsers being able to use their stuff. Google is in a position of power here: they are the #1 search engine, they are the #1 browser, they’re pretty well positioned on the mobile phone market too. The vast majority of businesses (companies or individuals, doesn’t matter) simply can’t afford to go against Google.
If the vast majority would, then yeah, Google would backtrack. But that would require a coordinated effort, from the vast majority of the internet. Likely multiple months of protest. That’s not going to happen, people can’t afford it.