Different extra feature for the regions, there is very little reason as to why a region A or B should have different features.
I think in terms of Blu Ray it's due in part to what the features were when released onto DVD. A lot of R2 DVDs didn't have the R1 extra features, and when they've since released the movie/series onto Region B BD they haven't bothered doing the extras as they'd have to go before the BBFC for classification.
It does seem to be less of an issue nowadays though, luckily.
what annoys me is half seasons. It's a shitty attempt at a double dip and I refuse to bite
God yes. Even worse, the Stargate SG1 releases - 4/5 episodes per release, and then 5 releases per season, and not even the option of a full season set until much farther down the line (season 7 or 8 onwards).