There are lots of good reasons for media to cover the Petraeus affair:
- risk of blackmailing CIA director, who avoided admitting this indiscretion for a while
- bad judgement of Petraeus (why not use secure communications? why have an affair?)
- bad judgement of Gen. Allen (why email Kelley so much? why vouch for her sister in custody case?)
- military access granted to Paula Broadwell, a "journalist" who needed a ghostwriter
- military access granted to Jill Kelley, a volunteer with lots of debt, a bogus charity, and other bad judgement
- unprofessional FBI investigator (shirtless with Kelley, and leaking info to congresspeople)
- exposing the excesses of Tampa's social life
- pointing out the ridiculousness of expecting monogamy from military personnel stationed far from their spouses

Also, it's a great soap opera.