Because an identity is what allows you to exist as an individual within the world.
A newborn baby doesn't have a conscious mind. It has senses and it can feel, but it can't make sense of any of the things it feels. It experiences pleasure when feeding, but it can't distinguish between the object giving the pleasure and the body receiving it. It isn't aware of having a body at all.
At some point in human development that baby becomes conscious of a distinction between itself and the world around it. It realizes that the thing that gives it pleasure is outside of itself, and by extension it begins to develop the understanding that it is a distinct object. At around two years old, it begins to recognize this object (its body) in a mirror. By around four or five years old, it has begun to develop a basic theory of mind. It understands that it has internal thoughts which are distinct from its external body, and on a very basic level that the bodies around it also have internal thoughts. Thus, it can figure out that the body it sees in the mirror is what other people see when they look at it. It is a unique individual among other unique individuals, similar to them but not exactly the same as them.
Identity isn't just a set of arbitrary categories that we place ourselves in, it is a basic, fundamental and involuntary recognition of our position within the world. That five year old child knows whether it has been assigned as male or female based on the appearance of its body. It knows that it is supposed to be similar to people of the same sex and a distinct from people of the opposite sex, and because children are finely-honed machines for observing and learning behavior, it can also infer from the behavior of those around it what this distinction means for its position in the world.
That child is also, in all likelihood, already well on the way to figuring out how it feels about that position.
To be a person, you also need to not be any other person. That is a "restriction" and you could, if you wanted, frame it as "repressive", but doing so is ultimately meaningless because there isn't any alternative to being a person. Other than dying, I guess.
Perhaps you could deign to credit others with the same ability.
Queer life is harder in some ways and some people break under that hardness, but it can also be extremely joyful, liberating, empowering and beautiful. It is a life none of us chose but which is worth choosing.
Think about it this way. You may not actually like the social visibility of queer people, but you need us. You need us because if we didn't exist and if we weren't visible you would have nothing to measure yourself against. You can only pretend to be "normal" or claim this bizarre value you place on being part of the majority as long as there is a minority.
We, however, had to get used to not being normal. We had to build a self and a happiness separate from the value placed on normality, and as a result we don't need to define ourselves in relation to you. You are dependent on us, but we don't need you at all.
The fact that you live in fear that "normal" people will repress their own identities out of existence by pretending to be queer or trans, to the point of suffering discrimination and hardship, is just telling on yourself. If you really believed that your life was joyful, if you really believed that it was sufficient to make you happy, you shouldn't need to worry about that.
Me too.
That emotion does not require you to have sex with someone, and it certainly doesn't require you to only have sex with someone. I certainly don't see how it justifies intentionally living a "tragic" existence.