Honestly, I really never understood about that whole tarnishing the show's rep thing. I remember having a similiar discussion in The Shield fourm for that show's ending run.
At the end of the day, once a show is over, and it's over. And there's only a certain amount of DVD re-runs you can watch before the show gets stale. Why not pump everything the show has out, and if the quality does end up suffering a bit, at least you gave it a shot.
Everyone seems to be more or less agree that S6 P1 of the Sopranos wasn't on par with the early seasons, but does that mean you think less of the show when you think of The Sopranos? Wasn't the saying always "The Sopranos at it's worst episode is better than 90% of TV on it's best season"?
I'd love a 6th, 7th, 8th, and 100th season of The Wire.