I agree that Y is a much bigger issue than F.
NW domestic F isn't designed as a true first class. It's a super coach product offered free to elites as a loyalty driver: a little bigger seat, free drinks, an occasional, random chance of a meal, but that's it. It is not conceived as a competitor to CO or UA domestic F and I don't think they're going to do anything to "fix" it.
That said, I hate flying in Northwest Y, particularly in back on the 753s which offer the worst experience a person can have on a United States domestic mainline flights. There is no way I would stick with Northwest without an elite card, and we're still waiting to see the true effects of elite-inflation, e.g. how often Plats and Golds will involuntarily sample coach this year. The sorry state of Y is NW's real problem, because while F is a moderate loyalty driver, Y is a serious loyalty repeller.