Well, in my view it's better to have something put back. As long is it is faithful to the original plan and scale (I imagine the layout was still completely apparent, or at least recorded). Obviously the earthwork isn't strictly "original", and the methods of construction "inauthentic", but does it really detract? By having the earthwork restored, at least the site's landscape context is also restored, which to my mind is an essential aspect of any prehistoric site. Also, it presumably will make it less likely to be ploughed out again. If it had been left, there was a fair chance of the rest going the same way.
Finally, it may provide a useful opportunity to measure erosion, etc, like the experimental earthwork on Fyfield Down.
Perhaps it may serve as a hopeful example for Priddy's future?