There may be some middle ground between 'yahoo, he should have played the whole game!!!' and 'he has one assisted tackle for the season.' There are few players in the front seven who play the whole game ('!!!').
No one expected Cunningham to play every snap of every game. However, there was hope he would contribute, maybe playing 30 snaps a game, generate a couple pressures and hits, set the edge on the strong side.
I see little venom or pitchforks, simply disappointment. Would many of us like to see Cunningham earning as much time as the group above - Carter, Anderson, Ellis, Deaderick, and Ninkovich? Sure. He's a second round pick. Deaderick was a seventh-round pick from the same draft on PUP. Ellis is an aging vet. The team needed to go get Carter and Anderson because of the lack of performance of the 2010 players rushing the passer last season.
Disappointment in Cunningham isn't quite 'sky is falling' territory. Nor is it sacrilege. Much like the 2006-2007 offseason, when the cry was for receivers, over the past two seasons many fans have pointed to a lack of effective pass rushers. The concern was real. The team reacted. This offseason, Cunningham was seen as a potential solution after starting 11 games in 2010. He's not.
Cunninghan is a disappointment. Calling that label incredible negativity? That's not setting the bar for disappointment very high.