I think a lot of it comes down to creating beer intended to be consumed cold that doesn't taste as great at a different temperature. Chicken soup is delicious warm but cold it's not so great.
I wonder how much of this is psychological built out of marketing that beer is supposed to be frigid and warm beer is really bad. As a result tasting the different grains or yeast character is treated as "bad" flavors when that would be a positive in most other beers. If you have been convinced those types of beers only taste great when they taste like cold white bread then you would reasonably expect to consider other normal beer flavors as bad or off.
I also wonder, conversely, how much of that is disdain for BMC. Lots of breweries are making corn and rice adjunct lagers calling them creative names like Japanese-inspired rice lager. I wonder if these craft versions of industrial lagers inspire the same disdain at warm temperatures.
The marketing is certainly part of it. Not only are they supposed to be drank cold, but as quickly as possible, so who cares about taste? Coors Light commercials use the word cold 16 times and never once reference taste. Those commercials drive me nuts, because they aren't lying at all, but they focus on "cold filtering" and "cold packaging" as if they were the only ones doing it, rather than the industry standard that every brewery on the planet does. I'm sure there's a word for it, but it's deceptive. It's not untrue, but they aren't "special" or different for it.
My father-in-law and brother-in-law are Coors drinkers (sometimes Miller Lite) and I would agree to the "thinking normal beer flavors are bad" is true, because you give them anything with dark malt or hops in it and they make bitter beer face. I think they could eventually like it because it is an acquired taste, but they are pretty set in their ways and likely aren't going to change. I'd imagine most B/M/C drinkers are such, they've been drinking it for 40 years or are new to beer and like Coors Light specifically because it's flavorless.
As far as other lagers, I think it's half perception and half that some of the other ones are simply better. I'll admit I do like Pacifico a lot, and most of the Japanese beers like Sapparo and TsingTao which are also rice but in my opinion "cleaner".