Makes sense...
...to have parallel systems. After all, what would have happened to the ISS, during the groundings of the Shuttle fleet, had it not been for the Russian's Soyuz?
And if Orion end up like the Shuttle, i.e. over-promised, under-delivered, complex, expensive and unsafe, maybe, just *maybe*, a Euro-Russian-Japanese would fare better.
Ah, who am I kidding? International efforts usually end up being the worst examples of "design by committee". Like the ISS.
[To the editor - please ignore my previous two posts, which have the wrong Title. Browser trouble, so sorry.]