You often have much more information at runtime than at compile time. Sure I can run the compiler and scan its errors but I feel its much more productive to poke around the program as its running. Even when working in C++/whatnot I learn more about programs by running them in the debugger than reading the code (reading UE4's source code will be weeks of head scratching because its so huge - 2 days of stepping into its boot process and you know and _understand_ most of its architecture).

I'd argue that the hardest bugs to find are the ones your type-system is completely helpless against. Few languages protect against null pointers and every time you have a cast you're breaking out of the type system and its guarantees. Dependent types aren't frequent either so you're now augmenting the type-system with asserts and guards and whatnot.

I find that in C++/Java/C# complex systems are the norm because everything is built out of mutable blocks and misconceptions about what makes programs fast.

Every project I did in Clojure was a fraction of the complexity it would've had in imperative languages. You're reducing complexity _so much_ that the "type-system is good for complex bugs" argument almost vanishes.

Agreed - in Ruby, most of my development was driven by a REPL & debugger, and tests. That's an example of a primarily imperative language, though it borrows some ideas from Lisp. But there, again, understanding error messages was key.