> I think they even haven't adopted newer JVM features

You don't know what you're talking about. Not only Clojure steadily adopting newer JVM features (for when that makes sense) - java streams, functional interfaces, qualified method values, interactive lib loading, JDK21 virtual threads, etc., Clojure constantly explores beyond the JVM - e.g., Jank targets LLVM and has C++ interop.

Pick some hardcore JVM topics and try searching what Clojurists think about them - GC, profiling, concurrency, etc. There's tons of interesting, deeply involved things constantly being hacked together by incredibly knowledgeable folks. You're casually name-dropping "complexity" maybe without even realizing that it's a community that includes people who have written production experience reports on Shenandoah GC, built profiling tools that work around safepoint bias, and given conference talks on tri-color marking algorithms. Dealing with complexity is their bread-n-butter. Challenging Clojurists to debate about "complexity" is like dropping "the brain has neurons" around a group of neurosurgeons. They'd quietly say nothing, so you can "win your argumentation", but they'll just... know.