If using that line of logic, Do you also complain that you can't change your face?
Tattoos are an extension of your identity that you get to customize to your liking. The art is an expression of who you are and your body is the canvas. Of course you might think it not necessary or pleasent but to quote The Dude: "Yeah, well, you know, that's just, like, your opinion, man."
Personally I don't have any but If I did they would tell a story about me. And that story is my identity, my brand. You can then experiment with clothing that reveals different things if you like. I have a few friends that get deep into the art and fashion they use to accentuate them. It does have an appeal and to some looks attractive. YMMV, etc.
Why do we cut our hair, trim our beards, make music, pierce our ears or wear clothing? None of these things are strictly necessary.
The Ancient European Picts, Mayans, Native Northern Americans, Polynesian islanders, all of these humans were HEAVILY tattooed, often with ritual significance.
Tattoos are an ancient human art form. Ötzi the iceman had visible tattoos.
It is a way to memorialize the past and express yourself.
That’s fair to not get it. Being tattooed isn’t for everyone. I’ve wanted to be tattooed since I was 12. Not really sure why other than I was drawn to it. I’m 30 now and have about 30% of my body tattooed and have no plans to stop.
To address the potential startup — there are a handful of companies that sell temporary tattoos that last for several weeks, but they tend to favor trendy things (think infinity symbols, tribal (not really trendy anymore), and simple blackwork). I did see toddlertattoos[1] today, and those look really great. The biggest barrier to entry is the industry itself. It’s incredibly inclusive, closed off, and reputation based. I don’t think a person who doesn’t have a huge reputation in tattooing could make it work.
I do think there's market for more colorful, longer lasting temporary tattoos. (Might be a startup idea for ya)