Because the clips are from the band's master copy. Almost always, the bootlegs don't look or sound as good as the masters, because they've been copied many, many times.
But for many concerts, better versions have been found. There are A+ versions of many concerts now.
I truly hope that they would get the grip and release this wonderful concert. Let it be an mixture of both nights (6.6 and 7.6) if they had some vocal mic problems on the other night, and if they want to make sure that the best version of each song will appear. The stage set and the costumes were same anyway.
On Rare Live and Magic Years, there is a lot of good footage from these shows. As we can see: QP has the master tapes and can get the best out of them if they like.