The point of insisting on capitals numbers and punctuation is to widen the 'alphabet' a cracker needs to iterate through. I'm totally with XKCD here: use a set of seemingly unconnected words - those are much easier for humans to remember (from not having seen that XKCD cartoon for at least 5 years I remember "correct horse battery staple") and increases the 'alphabet' to the number of words. Add in some capitalization (even simple camel case) and that number more than doubles.
[edit] do NOT use "correct horse battery staple" :-) [/edit]