One other characteristic obtained by shortening is brittleness. "Mammy's little baby loves shortening bread..."
And flakiness depends on repeatedly rolling the dough out very thin, folding it and rolling again, and I think flour dusting between rollings.

P.S. Here's a URL with all the details:
http://www.allrecipes.com/cb/kh/pie/piecrust/default.asp
And the physics and chemistry are so complex, ordinary chemistry courses don't attempt to discuss it. It's a black art, not a science.