That argument doesn't really hold though. You're not upgrading your base(the OS) to fix the problems with it yet you're complaining about a minor(in the grand scheme of things) library removing support in a modern version. If your network is closed off like the NHS one you mention, why not just stick with the old versions you've already fixed?
It's like complaining your 56' Chevy doesn't work with the new battery technology coming out in the Chevy Volt.
The problem comes is that the older versions that we've fixed have the fixes integrated in later versions.
We really don't want to have to maintain the versions that we've fixed as that kills the entire value proposition of using it in the first place.
It's nothing like the 56' Chevy / Volt analogy. The technology is the same - they just can't be bothered with supporting one vendor's product any more.
Why do those fixes matter? Again if you're in a closed environment then you can surely control the versions of a JS library. So fix it until it works in your space then move on. Them dropping support for your outdated choice of platform isn't a problem. Your desire to use cutting edge software with your outdated platform is the problem.
Picking a platform and sticking with it is a nobel and occasionally needed position to have. Expecting everyone else to hold themselves back because you chose to do so is impossibly greedy however.
It's like complaining your 56' Chevy doesn't work with the new battery technology coming out in the Chevy Volt.