Resolution isn't the only factor, but to call it a non-factor is absurd. All else being equal most consumers would prefer to watch the same movie or play the same game at a higher resolution. It should be absolutely self-evident given that re-releases of titles this generation and last have done well when often the only differences from the original release are frame rate and resolution.
It does get a lot more subtle when you're talking about trading off resolution for frame rate, gameplay, AI, or complexity of visuals. Those are entirely legitimate discussions. The "1080p doesn't matter" argument on its own is simply disingenuous. Of course you could argue that Ubisoft isn't necessarily trying to convince us, they're just trying to turn the conversation back to focusing on the game itself and not the poisonous spec competition. They have a product to sell, after all, and it's not a console.