Look, I get that there's a uniform dress code in the NFL, and that rules is rules. But in this particular circumstance, pushing pink gear throughout certain weeks of October to raise breast cancer awareness, then banning it every other time, looks particularly awful. Especially considering that a player genuinely affected by breast cancer (or domestic violence, etc.), and who lives their life working to help its victims, is about as an effective a beacon as the league could want if they were truly devoted to the cause.
"But if they're allowed, everyone else would want exceptions ..."
Personally, I wouldn't mind if that happened. The fact that everyone's socks are on exactly right isn't why I watch football. But OK. Even if such an exception is a slippery slope to full-on uniform anarchy, it's the league itself that gave the first push down that slope by involving itself in such causes. If nothing else, it could let its players choose to extend its involvement with officially sanctioned organizations. That would please the players and organizations, and make the league's part-time promotion look more genuine.
I know as a fan, I wouldn't be offended. Quite the opposite, in fact.