I agree that the view from the top of Silbury Hill isn't the best view of the area. However, I think that the view from there is very relevent to the meaning of its construction. And if we are denied that view, then we can't possibly have a credible opinion of why Silbury Hill was built. Surely, the view from the top is crucial to the debate on why it was built. It's like saying that the orientation of the Stonehenge Avenue means nothing with respect to the construction of that monument.
Silbury Hill is a hill. Why is it a hill? That is the question. It's big, and has a flat top, so that has to be important. Is it for a view, or is it for size? If just for size, then why such a flat top?
As for access to the top, well, that is a topic worthy of debate. Control is necessary, but access has to be within that control. Otherwise, why preserve something that no-one can see?
Cheers,
TE.