OH2 vs OH1 stability. OH2 sucks!

You’re the first and (to my knowledge) only one to claim 1.X isn’t working with current Java, and it just isn’t true. I’ve been using it with Java build 1.8.0u131 (like you) and even 1.8.0u144.
The point is: Your specific setup doesn’t work with it, but many others do. And if you forget to save ‘your’ java before upgrading, don’t blame others, please.
While I understand that’s an annoying situation, it does not entitle you to put up this claim, or, worse even, to blame anybody for “outright letting 1. die”.
I repeat: Get engaged to make 2.X work for you. TRACE. Submit a useful GitHub issue.

PS: searching for libNRJavaSerial yields a number of results like this one. I had seen it at times, too, many others did. All issues I saw turned out to be config related and could be solved that way, such as the openhab-transport-serial bundle not being loaded, bad permissions on serial interface, or the serial interface name not being passed to java binary on startup.
So it’s unproven and even unlikely that your problem is a OH1 code Java incompatibility issue.