You can't possibly know what it's like to be trans
Is this really true for all people who don't id as trans? I've had body dysmorphia (connected to pregnancy and disability, not sex or gender). I've also for years wondered if I was trans - because I don't have an internal sense of being a woman, just am treated like a woman by society, have my life choices limited and so on, because of what is between my legs. I've finally come to the conclusion that I'm not trans (because if I surgically transitioned I'd just be looking at the same circs but from the opposite side of the mirror, so no change except a lot of paperwork, and I think the privilege I'm most missing out on is being socialised as a male, which I can't change), but I'm also not not-trans, either. I've seriously considered presenting as a man when I get older - not transitioning, but socially - but I don't think my body type would let me get away with it. As I said upthread, I think there's a lot of people in my general state of mind, once they begin to think about it. It isn't a particularly unusual state of being, but pretty normal, IMO.
So - I suppose that partly answers why more people are transitioning now than before: because they can, and because it is more discussed. I think the other answer is that gender roles are being more and more strictly enforced, and so this "I like dolls so I must be a girl", I like ties and machinery so I must be a boy" is getting more traction, when we should be moving away from all that shit.
And I have seen trans people online talk about their lack of dysphoria, and I've certainly seen plenty of trans women speak about their comfort with having a penis, how it's a "female organ" quite, quite different from a man's penis.
tl;dr: There doesn't seem to seem to be one size fits all with either trans or non-trans experiences, so I am not convinced that none of us who don't id as trans can possibly understand what it's like.