I think that a lot of it has to do with the filming. I think the guys who made UP were knew to filmmaking last year, and did a very good job in light of that. It takes time to learn what translates well to film and what does not, even if it looks good in real life. For example, some angles make fairly easy terrain look impressive, others make impressive terrain look weak. Same goes for skiing styles.
But more importantly, the more established ski movie groups (TGR, MSP, WM) all shoot way more film than UP. UP made the decision to make a 16mm film, which they had to do to be taken seriously and make the film quality look professional. But 16mm film is EXTREMELY expensive. With their very limited budget, they couldn't shoot anything near what the companies that they are being compared to shoot. I'll bet TGR and MSP shoot 20 or 30 times as much film, and that all comes down to sponsors and money. Building a track record gets you closer to the money, so hopefully UP can build their budget each year.