They, the Beatles (and then I promise I'll stop over-using their name), were great by any account: record sales, influence, sound, innovation, catchiness...on and on and on. People love them. They have done for fifty years.
So, when I say it's a little wrong to say you like them what I mean is this: of course you do. Why are you wasting part of my finite existence with this useless bit of non-information? Literally non-information: I am not informed of anything.
It'd be different if it was something a bit offbeat or sub-pop like Star Wars (although, for similar reasons, YAWN!) that only 90% of the population likes. But even then, what am I informed of, really?
Don't get me wrong, there is nothing wrong with liking these things.
It's just a real conversation killer when you say something as ubiquitous as "I like air."
What should the next line in the conversation be? What can it be?
Now, if you say you don't like the Beatles, you might have something tremendously interesting to say in the way of an explanation: you have issues with their lyrical content, their song structure, something along those lines. That's a fine and informative thing to say.
However, if you don't like them "because they're so overrated", then please, hit yourself in the face with a frying pan. (Because NOT hitting yourself in the face with a frying pan is so overrated).
No, but seriously, are all of your opinions dictated by other people's opinions? Always doing the opposite of "what everyone does" isn't any more interesting than just going along. Only in this case, it isn't that your own view is uninteresting per se, it's that you don't have your own view. You are just a reflection off of everything else. What use is that?
(Being useful is overrated)
(Sorry, I couldn't resist)