2) no shit. What business user is every in their mind prioritising upgrading their language version? It's not up to them to push the upgrade. It's yours.
3) of course they are. People don't desire what they don't want. Invest in people who are actually interested in improvement of their software.
4)the java team have been pushing heavily via twitter / youtube / infoq / hacker news / other open jdk providers all the new features for every single java version during their 6 months release cycles. If your devs / your team don't know about it, then maybe again youre not encouraging people to want to improve on what they have, or take interest in the tech they work in.
I mean that is fine, do I give a shit what java version in using for my take home salary? No...but I enjoy using the newest, most interesting and useful tools. And you best believe those people are more attractive to other companies and you working on some 15 year old java 8 tech.