Man, it's tough. The things I don't like right now:
--Parity is good, but games/seasons/championships come down to official interpretations way too often. Like the Dez-catch, or the unsportsmanlike conduct penalty for Cowboys fans. Or the way DET got jobbed in ATL this season. If every game is a toss up, there's not as much meaning to building a winning franchise. I like parity to a degree, but they've overdone it.
--The rulebook contains too many judgement call rules when it doesn't need to. I mean, what's a catch again? It's ridiculously convoluted in terms of what's a play and what's a clean hit. Again, opening up too much for interpretation and putting way too much onus on officiating.
--Officials should be year round, and there shouldn't be so much variation between groups of officials affecting outcomes of games
--The league is saturated, with too many games available on too many nights. Having more content accessible to more people is obviously good for the league, but we're past a saturation point where you get diminishing enthusiasm for even the good games.
--The league has an appearance of bias for and against teams, especially in favor of specific agendas they think will probably advance viewership. Domestic violence, marijuana, etc. Not stepping into the details re: those issues, but it's ending up with players getting unnecessarily suspended and teams not getting treated fairly relative to the rest of the league and coloring the results of seasons. Goodell has tarnished the shield more than any commissioner in history. He's terrible, and he's the front-man for the appearance of an ownership money-grab that makes the whole league look sketchy. He's got to go.
--Finally, they need to insist on a higher quality of coverage of their product from their sports network partners. The cheesy orchestrated 'debate' format shows where idiots yell nonsense at each other for 5 hours per week contributes to the air of sensationalism that's hollowing out the brand. They need to insist on a better quality of coverage.