I agree that a great story would be... great. Like you, I will look passed a game's faults if the story and cinematics suck me in to the universe. An example of this that I'm currently playing is Devil May Cry 4. I suck at it, I'm playing on the easiest difficulty and I'm still having trouble, but I keep going 'cause I love watching the cutscenes.
I apologize if I've missed some of your other arguments, I just noticed the back in forth going on about the "on-rails" gameplay, and to me, that's what the "feel" of a Star Fox game is about.
The problem that most of us have with recent Star Fox games is that they are NOT SF64. That game is a true Nintendo classic, and the majority of us just want to see the franchise return to that level. For me, it struck a perfect balance of difficulty and fun. The original Star Fox, although a great game, was way to freaking hard for me on the harder paths, and I could only ever beat it on the "primary" course.