Of course its complicated for no reason. Its an example! The same logic would apply if I had 5+ nontrivial lines of code instead of just a print statement.
I'm sorry, hardly ever had an issue with callback-based programming. If you're used to imperative, maybe the problem is that you're making a mess because you're adapting from a different style and complicating it with workarounds, you need to be functional.
I dont think its a matter of functional vs imperative. In fact, functional languages give some of the best tools to avoid having to write callbacks by hand. For example, in LISPs the language tends to have explicit support for converting non callback code to CPS (call/cc and thigns like that) and in Haskell you have do-notation to get rid of the nesting and hide the callbacks behind some syntax sugar.
