Because nobody dislikes an aggressive D. They're fine dying by the sword. Bottom line is the D gives up big plays, lots of yards, too many penalties and lots of points every game. They should be complaining about the D as well as the O. People see the D play well for a few drives and go, "The D came to play!" and excuse all the drives & points they give up the rest of the game.
The D has all the talent yet comes up small almost every week. The O has a 3rd string, practice squad QB playing and they blame the offensive coordinator.