A good deal of the whys didn't appear to justify or offer any sort of rational grounding to a number of Jewish practices, I understand their commitment to Torah, but the application of it and the basis for many customs seemed pretty out there for me. Many of the whys behind certain customs went back to medieval superstitions, and beliefs in magic. A number of custom were the result of some rabbi creatively adapting a word or concept from some completely unrelated biblical passage that had nothing to do with the custom at hand, other customs are simply because some rabbi said so.
If one wonders why Jews can't eat cheese burgers and must have two different refrigerators, and ask why, one is told that it is because the Torah says "Don't boil the kid in its mothers milk", to which one again wonders WHY for this prohibition has absolutely nothing to do with not eating cheese burgers. To this one is told some Rabbis interpreted it so. At which one wants to ask WHY would other Jews and rabbis accept such a ludicrous, groundless and off the wall interpretation? This is the kind of why question that Kolatch doesn't address. If the basis for such practices are really this loose, practically anything can go, no matter how off the wall and absurd. I just wish for some sort of justification or rationalization. Gee... if I was a Rabbi and read those who have a wet dream are unclean and must go outside of the camp, and said this passage means men cannot sleep, or if they sleep, must be awaken regularly less they dream and if not awaken regularly, they must have their hands bound behind their backs. Surely people would react and say this a ridiculous application of this law, but such an interpretation surely is more connected with the passage, than chilling stake and cheese in the same fridge being prohibited due to a command not to boil a kid in its mothers milk!
I had a similar experience while listing to a book on the early church, much of the Catholic doctrine originated really early, and for many Catholics this is sufficient, when giving the why the church fathers adapted such doctrines and practices, it often comes down to early church authorities taking some random biblical passage completely out of context, or some bizarre and irrational line of thought that was a creative response to some issue at the time.
I guess really it comes down to authority, the WHY simply is that someone considered an authority said so. If pressed, one gives the reason why that authority said so, and it doesn't matter if the authorities "why" is ludicrous, based upon pagan superstitions, terrible hermenutics or fallacious reasoning. I suppose respect for the authority means one doesn't press further, it is not to question the authority or challenge the the authorities "reasons", or lack thereof.
Maybe the reason religious books explaining why don't attempt to give a rational and sensible why to many things, is this wasn't the basis on which ancient authorities formulated their ideas and customs, so they're simply undefendable from modern viewpoint.