Why need it be "second rate"?
VT grappling would be second rate because it would be made up by a VT person with no real understanding of grappling. It would be much more simple, direct and efficient just to learn real grappling somewhere that specialises in grappling.
There are very simple takedowns that work quite well. If one of those could be mated with the movements and distancing already within the style, it would be a benefit to the practitioner.
Why, given the strategy of VT, would taking someone down be desirable?
So, your claim is that this art that is a combination of the work of multiple people is now nearly impossible to change? That makes no sense. Small changes over time should happen naturally. And those changes - if made judiciously - should be fairly easy to work with and should cause the art to evolve as the environment does.
I see no point in de-optimising an optimally functional system
You are correct, of course, that training in BJJ will provide superior results to whatever might be developed within VT.
Then I would say lets stick with that as a plan.