Naruto and Bleach aren't amazing shows, but they're good enough as to not be shitty shows.
As much as /a/ bashes them, they really aren't bad series by any means. They're easy to get into, and are simply fun shows. I suppose the problem is that they get too popular for their own good, and overshadow series that are much better. Then the fans go on to be fags and declare that show "BEST ANIME EVAR" when they clearly aren't, and therefore piss off people who are fans of the higher quality series.
Thus, people who like Naruto/Bleach are bashed because most of them fit into the above mentioned category. And the RAGE goes on.