Two explanations suggest themselves:
- A supremely clever god made “the principle of least action” absolutely general in the workings of nature.
- Inanimate nature has no choice, has no will-power to do otherwise. In animate nature in general, parsimony is selected for whenever selective forces work on deficiencies – favored in the struggle to survive are those who can make the most out of the least. Humans are creatures of nature, but because we have conscious thought and free will, we consciously and freely violate nature’s thriftiness now and then (e.g. whenever we seek ways of getting more exercise); so obviously the principle of least action is not absolutely general.
Relative to 1, consider this from Pierre Maupertuis, a principal proponent of the principle of least action (along with Euler and Leibnitz), and a firm believer in explanation #1:
“The laws of movement and of rest deduced from this principle being precisely the same as those observed in nature, we can admire the application of it to all phenomena. The movement of animals, the vegetative growth of plants … are only its consequences; and the spectacle of the universe becomes so much the grander, so much more beautiful, the worthier of its Author, when one knows that a small number of laws, most wisely established, suffice for all movements.”
If I had an infinite amount of energy, I would willingly violate thriftiness all the time and exercise my body into much greater fitness, and in so doing show just how wrong Maupertuis was in claiming applicability to “all phenomena”; as it is, I rebel against least action and seek ways of getting more exercise now and then.
In like manner, if I had infinite will power, then I would never have succumbed to temptation and never will succumb to temptation. But I do not have infinite energy and thus I usually seek the easiest way or ways of doing things, and I do not have infinite will power and thus I sometimes fall into temptation.
In our universe, deficiencies rule the roost! In framing laws of nature, do not forget freedom of will, which although not absolute, is not zero either.
Along that line, if the god of statement #1 wanted man to behave like angels, he should have created a new race of angels with flesh and blood or he should have created animals like us but with hundreds of times more will power to resist temptation. Bingo, an angelic mankind! If god were half as clever as Maupertuis imagined, he would have done exactly the latter!