You know, this "Do not open or excavate mentality" is not dissimilar to the "Do not use Avebury or Stonehenge for modern ceremonies" mentality; both are fixed in latter-day interpretations of the place and as such are frankly irrelevant.
Personally I don't give a tinker's cuss what happens after a place is excavated (provided that reasonable steps are taken to preserve the site and its contents) but I do believe that information gained from an excavation at a place such as East Kennet would be a valuable addition to our understanding of these structures and their place in pre-history.