Because teleportation is murder. Whatever comes out on the other side may look and act like you, but isn't you, because you're now dead for having been disassembled by the teleporter.
Teleporters are interesting because when you think about it long enough, you realize the person on departure end died.
You think about it more... and if the person that comes out the arrival end is an exact replica -- down to the atom -- and, further, has internal continuity of experience... You realize that if you accept they died then you kind of also have to accept that the "you" of any given instant is constantly dying and giving way to the "you" of the next instant. That person living that experience at that exact moment will never exist again; they're dead.
So you're kinda back to transporters being business as usual again, but with a fun new existential crisis on the side.
In practice, I agree with you. The transporter scans, disintegrates, and reconstructs the thing being transported. But when the thing being transported is reconstructed at a subatomic level it is effectively identical.
I can imagine the society we see in startrek having already worked through the moral and philosophical implications. I would have loved to see that addressed in an episode tho.