But 'learning things before you need them' is a different thing. It should be something like "always keep learning towards your goals". And that's what people do. Unfortunately different people have different goals and motivators. That's why many will stay away from books and from exciting new stuff, as long as they still get to keep their job.
Since you talked about Scala, when I worked on my last Java project for a former employer (a period that lasted like a year) the architecture and the tools (imposed to us by upper management) were so bad, that I was desperate to find new things to alleviate the pain (that's when I read Code Generation in Action). When I got into a data-mining project I read something like 4 books in the research phase.
Nobody likes learning for the purpose of learning. It's a painful process if the learned skills aren't applied (not to mention that memory tends to garbage collect useless information).