out-of-order cards in the modern decks

[JustLikeYou]

Actually, the original reason for their reversal--though Waite didn't speak openly about it--is the alignments of the cards upon the Tree of Life. It is generally accepted within the Golden Dawn tradition that the cards match the paths in order, but only if 8 and 11 are switched.

Edit: Crowley later switched 4 and 17, but this move makes little sense to me and leads me to be suspicious of Crowley's work.

Second Edit: The significance of the difference between changing the order due to astrological correspondences as opposed to Tree of Life pathway correspondences is one of primacy. In the Golden Dawn, the Tree of Life is given primacy over both the Tarot and astrology. Hence, correspondences are drawn between the three symbologies in an effort to synchronize the Tarot and astrological symbols with the already accepted meanings of the archetypes as understood through the Tree alone.