Interesting that all of the discussion is rambling about IntelliJ in general (e.g. Is it slow? Is it better than this other IDE? Ermagherd, Java sucks! Etc).
Nothing about the actual specific topic, which is that one of the most prominent development tools in the Java ecosystem now expects the current Java version to be installed.
Expecting the current version might sound mundane to a Rubyist or Node person (and it might sound like a pipe dream to a wistful Pythonist!). However, it's a pretty big change in the Java world. Backwards compatibility is highly prized...and tool or library authors have always been reluctant to use current language features, for fear of excluding users stuck on old versions.
Back when I was working in "the enterprise world", it wasn't unheard to see shops still stuck on 1.4 long after Java 7 had been released. Up until a few years ago, it was sometimes still a big deal for libraries to start incorporating generics (introduced with Java 5 in 2004).
Java 8 was SUPPOSED to an even bigger shift than Java 5, with an even slower adoption rate. However, for some reason it feels like the opposite is proving true. I'm seeing tools and libraries move to Java 8 shockingly soon compared to past experience.
I wonder why this is. Perhaps after the rocky Java 5 migration, large companies embraced the practice of updating their deployed versions more frequently? Maybe it's Oracle releasing new Java versions every two years now, and being more aggressive about end-of-life'ing the prior versions? Or perhaps it's just that I've been out of the enterprise environment and working for startups instead these past several years, and the situation in large companies is still as conservative and outdated as ever?