It's true that Clojure is "weird" because it's a different paradigm. It's not just a different language like Ruby was, it's a different family of languages. It's going to be strange if you aren't already familiar with Lisps and/or functional programming.
To some extent, I don't think any "killer app" is going to change that, although it certainly wouldn't hurt. The concurrency features are pretty compelling in that space already.
Clojure's primary appeal is not, and cannot be, that it's easy for most programmers out there right now. The appeal is that once you learn it, it's a better general purpose programming language that runs on the JVM.
Yes, that seems to be the case: "you need to learn it to believe it". And I hope people take their time to learn it because there seems to be a few articles out there with the message of "I picked up Clojure in a few weeks and re-wrote critical piece of my software in 2 days and it works super-scale".
Maybe that's the power of Clojure?
I really think that it will take a few years before a select few (persistent users, not alpha-geeks) from the Clojure community can come up with some sort of breakthrough that replaces today's best practices, whether it is the replacement of the whole OOP/*DD-movement or the way testing is done, or something else, I don't know. But I do believe that this is what needed.
It's mostly a mental barrier. Clojure isn't inherently hard, at all, it's just different. Once you get the hang of it, you can start reaping the benefits fairly quickly.
Unfortunately, most people judge difficulty in terms of familiarity, so the strangeness is off-putting even if it wouldn't be that hard for them to learn.
To some extent, I don't think any "killer app" is going to change that, although it certainly wouldn't hurt. The concurrency features are pretty compelling in that space already.
Clojure's primary appeal is not, and cannot be, that it's easy for most programmers out there right now. The appeal is that once you learn it, it's a better general purpose programming language that runs on the JVM.