I remember that the Orion spacecraft was a thing when it had its maiden voyage in 2014. Nowadays, all I read about is the SpaceX Crew Dragon and Boeing Starliner, which are both running late. Soyuz seems to be done.
What would some reasons be for Nasa not be planning to use the Orion spacecraft to bring astronauts to the ISS? According to Wikipedia it's designed for "mission at or beyond LEO".