[recursivecaveat]

In particular I don't think its physically possible to test Orion components in flight very many times. It relies on SLS which chews through 4 space-shuttle engines every time, which even with unlimited money I don't think you could acquire a large supply of very quickly.

[cryptonector]

Not only that, but it has to reach much higher altitudes in order to also reach the much higher re-entry velocities that it will have IRL. That makes testing Orion very expensive. Testing Crew Dragon was much much cheaper.

[pavon]

SLS is required to get Orion to the moon, but there are other options for LEO tests. Exploration Flight Test-1 was performed on a Delta IV Heavy, and Falcon Heavy is also capable of launching Orion to LEO (and now New Glenn, although that wouldn't have been an option at the time NASA needed to start work on another Orion test).