The issue isn’t that the majority of people are straight (though I’d point to what we saw in the rates of left handedness once we stopped punishing it), it’s how we talk about it and the assumptions we make - and it’s about the disparities LGBTQIA+ people can face because of the specifically heteronormative way society is set up.

Marriage equality is a great easy example - the reason marriage equality was (and is, in so many places) such a big deal wasn’t just so we could marry just like heterosexuals - it’s because there are so many rights afforded to married couples that aren’t afforded to others. Healthcare access is the big one - in so many places, only married spouses are considered ‘family’ and able to make decisions for their partner, or even visit them in hospital.

To use your analogy, it would be like there not being any metal concerts, ever, because everyone just likes pop, right? Why would anyone want to go to a metal gig?