just something about the way Silbury looks today (give or take a few meters) that looks right.

I dunno, it strikes me as the opposite. It looks unsettlingly incomplete.

However, this doesn't necessarily strengthen the idea that someone removed the pointy bit. Equally likely, there was originally some sort of monument on top - and THEN it would look perfect I reckon.

(And the Silbury game would work beautifully as well).