As your wikipedia definition states, the vagina is the tube that leads "
from the uterus to the exterior", so it doesn't include the uterus or any of the internal organs, it just connects the uterus to the outside world (and to the vulva).
A vaginoplasty uses existing tissue to create a vagina, i.e. a tube that runs into the body from the outside - and also involves some sculpting of the exterior to produce a vulva and sometimes labia too. In the case of a vaginoplasty, the created vagina doesn't lead anywhere inside, so the internal end of the tube is closed off.
It's not an ideal word, but then "vagina" itself is ambiguous these days, since people do more generally use it to refer to both the vagina and the vulva/labia collectively, which is maybe what caused your confusion about it being "simply the outside". It's an inexact term used inexactly

.