I think there would have been a strong case for continuing with the original Amtrak designed cars, if there was any sign that Amtrak was going to grow by leaps and bounds. Absent that it is hard to justify maintaining a design group beyond one that is needed to put together RFIs and RFPs and carry out monitoring and governance of them from vendor selection, through order placement, delivery and deployment. Incidentally, the biggest main line passenger car purchaser in the US today is NY MTA (LIRR + MNRR) AFAICT. Their order sizes, which are much larger than Amtrak's has ever been, almost justify doing their own design, but they tend to work with vendors using vendor shell design to furnish cars the way they need. But as Walter correctly points out, the situation back when Amtrak was ordering Amfleets and Superliners was very different. There were no vendors that were not about to go under around to work seriously with, so a lot had to be done in house. Also FRA's revision of standards allowing CEM in cars was many decades away.