sven, I can’t speak for anyone else, but I tend to eat and cook on the “plain” side (but I wouldn’t say bland) primarily because it is cheap. I learned to cook from my parents, primarily my dad, and when I was a kid we didn’t have much. When I was growing up I think the only spice I remember seeing in the cabinet was paprika. We weren’t picky eaters as kids - our choices were just limited.
In defense of the “bland,” though - have you ever had REAL Mexican food? I mean, food made by genuine, actual, salt-of-the-earth-type Mexicans for everyday consumption? My husband tells me all the time that my chili - which I freely admit is the “gringo-est” chili ever made - has more flavors than his father’s. And my father-in-law WAS Mexican. All I am saying is: you want bland, then you eat pinto beans with 2/3 of your meals every week.
I will agree with you about parents who only feed their kids McNuggets and hot dogs, to a point. This is a problem - but I empathize with these parents. It is hard enough for my husband and I to find the time to make a proper meal just for the two of us. And with all the other stuff that goes along with having kids - sports practice, homework, etc. - it is sometimes hard to find time to cook anything. Unfortunately a lot of parents end up feeding their kids whatever they will eat, just so they eat SOMETHING.