It was seriously disappointing watching Kaguya rarely ever use her Byakugan, even though they appear to be her original eyes. I was hoping for an equivalent of a Mangekyo Byakugan which would have blown my mind away. I really don't understand why the Hyuga clan were so arrogant and protective about their eyes since the byakugan is not even as impressive as a fully developed sharingan.
I had a theory that the seal placed on side branches was used to control and limit the growth of the byakugan so that the side branches don't overthrow the main house. A part of this seal prevented side branches from unlocking a feared mangekyo byakugan, which would give the user immense power. I thought a characer powerful enough to unlock such a technique would either be Neji or Kaguya.
I also don't understand why the Hyuga's main fighting style is close combat, even though the point of the byakugan is giving the user a better RANGE of vision than the opponent.