The answer, of course, is that it is the experience as a whole that offers a payoff, despite the pain or annoyance of each individual inconvenience. I may not like sleeping on an air mattress, or exposing myself to mosquito swarms, but I do like sitting around a fire with friends, and I like the idea of being in the woods, away from the world. Mosquitoes and the other irritations are just the cost of doing business.
The Orthodox Jewish Shabbos offers similar pleasures, and similar costs. It's no fun to walk everywhere, or to work around the technology limitations in the kitchen but who thinks about any of that when you're sitting at dinner, enjoying a distraction-free conversation? Who laments work restrictions when you're full of food and drink and in the company of family and friends? What's not fun about shul? Where else do you get camaraderie, music, poetry, and soaring rhetoric followed by top-shelf refreshments? As a whole, the experience of the Orthodox Shabbos offers satisfactions as rich as the satisfactions provided by anything in the world and these satisfactions are available to you in full even if you don't accept every detail of the underlying theology. Do I need to worship Zeus before I can experience the power of Roman art? Does a Catholic need to agree with the Pope on every detail of Church teaching before he can enjoy Christmas? Of course not, and the same is true of the Orthodox Shabbos. Even if you know the KOA lot is a KOA lot and not the wilderness, you can still enjoy a camp out.
I mention all of this because I came across a post written by a no-longer Orthodox man who wants nothing to do with his childhood culture. The very idea of living through a shabbos makes him ill. Though I respect his choices, and confess to knowing nothing about his specific circumstances, the post still made me sad in the way, I suppose, opera enthusiasts are sad when they meet someone who doesn't like opera. Taam v'rayach ein lehitvakayach, of course, and again, I respect individual choices and recognize that there are always surrounding circumstances, and just as an opera enthusiast would not question the morality or character of someone who dislikes opera, I am not questioning the morality or character of an FFB who no longer keeps shabbos but still I wish that man and others like him could continue to enjoy an Orthodox Shabbos secularly.
A) Someone is going to ask, so let me answer up front: I believe in God, and I believe that Shabbos was His idea (though I know there is evidence for Mesopotamian antecedents.)
B) I also know that 99 percent of Orthodox Jews, including the most devout believers, are Shabbos observers only for the sake of the physical benefits. No one likes the mystical spiritual benefits of shabbos because no one has sensory organs that can experience the mystical spiritual benefits. The man who says "Oh, I can feel shabbos" is feeling the cholent in his stomach, or something like that. Because we humans don't have the ability to pick up anything but physical phenomena, its impossible to say that we've experienced anything but physical benefits. Even the rare individual who hates all the immediate physical benefits shabbos offers, but keeps it anyway is experiencing some sort of tangible payoff. Perhaps he's a masochist, or perhaps he gets an emotional rush from respecting God, or honoring promises he made to his family. I think that these benefits, whether they are experienced directly or not, are all secular benefits and the real reason people keep Shabbos and the other commandments.
Search for more information about secular Orthodox Shabbos at 4torah.com.