I have to argue semantics, because otherwise I can't tell if you're misunderstanding what I said, or what my purpose is.
Regarding beer vs. diet soda, I don't have to explain it, I just have to know how people react when something they like for whatever reason is taken away from them. The argument applies as much to beer and soda as sex and drugs. You read my post as though I'm making a tautological statement of fact, and I apologize if it came across that way. But the point I was trying to convey, which you seem to have missed, is that if people can find a legal acceptable substitute, they will. If they cannot, they'll find other, less-legal ways to get what they want.
But let's put that aside, and address your restated question. First, the thing to keep in mind is WHY do people drink soda or beer? You can't just focus on taste and ignore everything else.
1. Why do people who don't like a poor tasting soda not drink it? Because they can find substitutes. Why do people drink soda in the first place? My GUESS is for taste and caffeine.
Now, let's be generous and assume the diet-soda has the same amount of caffeine, but a worse taste. Thanks to the nature of markets, there are plenty of other sodas out there that cost the same, have the same amount of caffeine, but a good taste. In short, to buy the diet soda is to pay the same amount of money for an inferior product. Do you pay $1 for (caffeine+good taste) or $1 for (caffeine+bad taste)?
2. Why do people who don't like the taste of beer drink it? Because they're drinking it to get drunk, or socialize, or look cool. They're.not drinking it for the taste. Also, because they can't find an appropriate substitute.
What are the possible substitutes for beer as a method of getting drunk? Wine? Whiskey? The problem is that they cost more, or perhaps they're too strong. So if the person is a lightweight who wants to get drunk on a budget, he's stuck with beer.
To be fair, there MAY be taste issues regarding beer. I imagine that's why there are beers which taste of oranges, or whatever. And in those situations, if a person doesn't like the taste of a Miller's, they might go for the marginally less bad Blue Moon. Or vice versa, because taste is subjective.
Now, to get back to your demand that I explain why something tastes good, the short answer is: I cannot, at least not for everyone. Everyone has their own preferences. People who drink wine claim they can taste "a hint of cedar, apples, this is a full-bodied drink." Whereas to someone like myself, it all tastes like burning rat pee. Are they lying, or am I? Neither. Taste is a purely subjective issue.
Lastly, on what grounds do you claim that non-alcoholic beer is more popular than alcoholic beer? To me, non-alcoholic beer seems like a total waste of money, and could only appeal to the very small group of people who like the taste of beer, but don't want to get drunk.