People care but, as you say, just ignore them. And, why do people who drink their coffee black always seem to be bragging about it? Oh? You drink your coffee black...congrats I guess?
Short answer because it will makes you feel more refined as an adult who can appreciate things that kids cannot understand.
Long answer because as coffee enjoyer, I love to smell it with my nose then enjoying the lingering aroma in my mouth, to taste it with my whole tongue, seeking the taste that is hidden beneath the bitterness.
It can only be found in the fresh beans brew, different brewing methode yield different aroma and taste, different beans have different characteristic and flavour beneath the bitterness, some coffee also change flavour as the temperature drop. Not every baristas can show it in the coffee, and not everyone who drink it BLACK actually enjoys it.
It is sorta like opening a mystery box, will it be good will it be bad, what makes it good how bad it is, and the good relaxing smell in a cozy cafe is the cherry on top. It is calming and exciting, if you can find and understand those charm of good cafe coffee, surely you will want to brag about it the way you brag your new plastic model.