We don't know why. Could be for shallow reasons like that, could be for a specific in story reason. Either way it doesn't change their bad visual look.
I don't believe everyone whom you've met does not find them distracting in some way. I'm not saying they all do, but I think some do. Probably more than you realize. My personal belief is they are too polite to say so. Not trying to insult you or your friend, but anyone who draws on their face and body with tattoos, especially outlandish ones like a clown on your head, guaranteed people will find them distracting, especially if they're on the face. Just because you haven't had anyone say it to you doesn't mean they are not thinking it.
That's what I think.
Then you have the fact that the Joker is not associated with tattoos. By now audiences have a preconceived notion of what the Joker looks like. They didn't just add one or two little subtle tattoos to him. They added a plethora of big ugly eyesore ones, including one smack bang on his forehead. Naturally so many people are going to find them distracting, not to mention stupid.
Yeah and the reason some don't like them is find them to be an eyesore and distracting, especially the stupid damaged one on his head.
I'd say that goes for most people, myself included, too. But that doesn't make his visual look unimportant. Because it is. It's very important. No matter what reason the Joker may or may not have for covering himself in those ugly tattoos, it won't make them more visually pleasing.