re:Evolution
During the Apollo era, le Apollo 9 and 10 LMs were not meant to land on the moon with. A later version was.
Same thing here: why must the CEV be Mars-applicable before a first version even flies?
The Shuttle had to be completely built before it was first tested. A 6 years hiatus occured before the first flight (manned).
Here, at least, for the CEV, there is room for evolution.
Raoul