I understand where the OP is coming from, "Why watch if you don't like it?" but its not as simple as that, People have been fans of this show for over a decade,
I'd watched pretty much every series and while I enjoyed some and not others, the core format was more or less intact, or at least only moderately violated.
Of late though, its like the very ethos of the show has gone out of the window in the name of cheap entertainment. Someone else on here summarised this perfectly in one sentence by saying "We've gone from Celebrities out of their comfort zone to reality stars in theirs" - to me this perfectly sums up the problems, or at least my problem with the evolvement of BB - Putting people out of their comfort zone is, in my opinion, the fundamental key to the whole thing. Take that away and whatever you have left, it ain't Big Brother!
...Anyway, I digress. Long term fans of the show continue watch in the hope that they will see a return to form. I did for many seasons, this year I have watched the first few episodes and opted out. I still keep an eye out on here in case things change (the next stage of detachment

). Those that are disenfranchised with the show are all at different stages - some of us are still watching and being dissappointed, others watch on and off, some have given up altogether.
Its a bit unfair to expect people who have been fans for 16 years to just stop watching just like that.