If you leave the featured areas and venture into any of the categories, you will see that HBO is also full of junk. HBO -> Browse by Genre -> A-Z -> any of them are full of junk.
The Netflix featured pages are more geared to showing you stuff you haven't seen yet, while HBO is geared toward showing you popular stuff, even if you have watched it on HBO.
I got HBO to watch good shows and suddenly the frontpage was filled with promotions of this inane reality-TV crap that I didn't have any interest in really paying for.
Yes, Netflix has added some reality crap like those fixed Tyson boxing fights and similar, but the ratio of crap to good content was still in heavy favor of content (and most importantly, they didn't try to fill my front-page with the crap).