The Clojure example he gives of a closing paren stack that looks like ]))))])))) highlights the downside of the Clojure sugar for vectors. It's a lot easier to just keep pounding out parens at the end of an expression until they match up than it is to carefully alternate ] and ). This outweighs whatever gains were made by the vector literals IMO.
I think I would have preferred some standard reader macros instead for collection literals.
I must admit that I didn't start using paredit-mode until I began hacking in Clojure, and find it useful for just this reason. I have since 'seen the light', of course (and now have little idea how I managed to get by without it), but in CL it was far easier to, like you say, "pound the parens". So that's what I did.
It would be easy to add a nice electric-right-paren function to clojure-mode that would be bound to ')'. It would always insert the right kind of a closing paren.
paredit-mode (http://www.emacswiki.org/emacs/ParEdit) already provides a lot of functions for manipulating s-expressions, including keeping track of your braces.
But the thing is, you shouldn't be "pounding out parens", you should be matching each closing paren with its opening one. Which the usual indentation and other formatting conventions make easy.
Or, at least that's how I do it and I typically find a variety of mistakes while doing that explicit matching.
(In case I'm not clear, as I type each closing paren I move my eyes' focus left and up matching it with the corresponding opening one.)
On the contrary, for me, having the occasional } or ] in there lets me more easily visually match up blocks of code when using a non-smart text editor. They are like little beacons of light in the darkness :-)
I think I would have preferred some standard reader macros instead for collection literals.