Well, they probably weren't ideally placed to run stories on phone-tapping. Glass houses and all that...
You're also being too sentimental about the red-tops' role in life. The Mirror did exactly what you suggest - Piers Morgan very deliberately chose to ran a more "serious" editorial line than most of his counterparts, and ran far more stories about serious topics like the war in Iraq, MP corruption and so on. And the Mirror's circulation nose-dived.
The Red Tops have to tread a delicate line between sufficient tittle-tattle (for circulation purposes) and serious journalism. The Screws trod that line better than most of its other competitors (Sun - certainly an internal competitor - People, Mirror and Star).
If you're looking for damning indictments, look no further than the British public, which saw the Star's circulation almost double after Desmond chose a deliberate editorial policy to dumb down, go for more stories about t*ts, Jordan, and Big Brother, and who aimed squarely for the market that lay between the Daily Sport and The Sun (and who knew that such a market existed?!).
Incidentally, the Rooney/hookers story is absolutely news-worthy, whilst he and his wife continue to attempt to trade on - and make money out of - their supposed wholesome family image. Ditto Giggs. The story about Haton was, perhaps, less news-worthy, given that I'm not sure that Ricky has ever pretended (not that he had any obligation to) or sought to make money out of a particular public image.
Does Rooney really trade on his wholesome family image, or does he trade on being a fantastic footballer? Ditto Giggs?