James,
The problem of "mission creep" is inherent in all projects. Did anyone ever build a house and have it come in under budget? No... there is always the expectation that "well, as long as we are at it , we can just....." One of the big responsibilities of an architect or builder is to reign this stuff in, and be able to tell a client "yes, this can be done in principle, but it is not good for you and you would not like it."
My experience with software designers is that they are much less good at limiting their imaginations than many other trades. Software design is cool, it attracts very bright and creative people, and the urge to strut your best stuff is overwhelming.
What Leslie is saying is that some of the "cool" things that have crept in, to make the permutational N! so much bigger, are the result of lack of restraint. Someone should remember the Talmudic saying: "The wealthy man is satisfied with his lot."
