@ConfusedImp Fun fact: while this is one of the strongest grammatical rules in English, there is one exception: when two successive words are sufficiently close to reduplication with altered vowels, front close vowels always precede back open vowels. Hence "big bad wolf" instead of "bad big wolf".
@Rosemary @ConfusedImp Sort of? A blog by linguists points out there have been a number of studies showing this isn't a strong rule at all: The examples are just cases it works http://languagelog.ldc.upenn.edu/nll/?p=27890
@ConfusedImp This is also why words like wishy-washy, flim-flam, mish-mash, and phrases like "fi fie foe fum" are in that order.