I agree with much of what's been posted here. My own list would include:
1. Predictable offense
2. Much of the defense...soft, vanilla, lack of a killer instinct
3. Inability to go for the jugular after building a lead on an opponent (although there were a couple delightful exceptions last season)
4. Failure to supplement draft picks through free agency
5. Dearth of impact players selected in the first round of drafts, especially on defense
6. Lack of accountability among coaches and players
And finally, I'd like to piggyback on your post, Empty. The Packers' fan base is as devoted and loyal as any in sports. There's a remarkable sense of investment in the team--and not merely among those who are, well...actually invested. It's ubiquitous throughout those that follow them. And that's one of the many things I love about being a Packers fan. However, this quasi-familial aspect of fandom sometimes lends itself to homogeneity and blind adherence to all team and front-office decisions, regardless of how ill-advised they may be. As a result, anyone who questions these choices or offers a dissenting opinion of the Packers management is criticized and has their identity as a fan called into question. I find this appalling. Admittedly, it's generally a practice reserved for the weak-minded who are unable to postulate a logical and thoughtful response, so these types of condemnations can be easily dismissed. Nevertheless, it's a problem I find much more pervasive among Packers' fans than I do supporters of other teams.