I think the problem is that, like movies, certain games set a standard that becomes damn near impossible for the rest of the gaming community to live up to. People may claim that games don't get worse with age, but I feel this is actually a true statement - as technology improves, and games get bigger and bigger budgets, many times the games just get flashier and flashier with their presentation, and more and more innovating with their various gameplay styles. This causes, as you said, expectations in general to rise, and when older games are subject to these new expectations, they don't come anywhere close to what we've come to "expect".
For example, take the "open-world exploration" genre; I'm sure a vast, vast majority of today's gaming audience would award The Elder Scrolls: Skyrim the "best-of" title in that genre. Skyrim set an incredibly high bar, and if a particular game that fancies itself an "open-world exploration" doesn't prove to be on par with or greater than Skyrim, it's deemed "disappointing" or a "failure". We can see this same kind of phenomenon with movies, particularly in the super-hero genre. The Dark Knight is considered to be the absolute highest point of the genre to so many people right now (including myself) that nearly every single super-hero movie's bottom line in the review is "How does it stack up to The Dark Knight?". This creates an almost unfair comparison, just because of how great The Dark Knight was, so much so that it actually does a disservice to other movies that are damn good in their own right, just not as good as The Dark Knight. An example in the gaming industry is the multitude of platforming games, indie or otherwise, that are eternally pitted against the likes of Megaman 2 or Super Mario World - these games were at the height of the genre, and are STILL considered to be near perfection in the genre to this day, making it incredibly hard to even compare to them in the modern age.
I do think that, unlike movies, games will progressively get better.... hopefully. It's hard to imagine cinema having many more breakthroughs than it already has - the best movies are still the ones with the best story and/or action, and better CGI won't really change that. I feel that games have much more room to grow, because they can always approach the medium from a different light with new innovations in the gameplay department. I was wondering if Skyward Sword could set such a bar of perfection, but in hindsight and in history, I think its approach to gameplay and controls will be remembered as little more than a novel gimmick that fell out of favor, almost like the rhythm game genre. There's still ways that games in the future can "surpass expectations", although it'll get harder and harder as time goes on. I still personally find a great deal of satisfaction from a game that lets me try new ways to play, like Epic Mickey, a game that isn't all THAT great, but had a neat little gameplay style that was at least memorable in some form, and I expect some future games will make me feel the same way.
