I'm going to try and go beyond the OT and delve into something that has bothered me ever since I've been old enough to reason. This is also part of the reason why I believe video games, of all stripes (PC, Console, etc.), are one of the best ways of producing and evolving ideas, with comedy and music vying for a close second and third, respectively.
Corporations and such want to keep gaining the highest profit imaginable while keeping costs at a minimum. Such is how it will always be with any gaming company. While this alone doesn't keep games from being their absolute best, it does have one serious setback when combined with another factor.
Religion. And before any of us go debating this aspect of humanity on this thread, let us first see how it impacts this field. At least, according to me. You'll probably have differing views.
Religion, for the most part, has instilled this kind of fear, shame and guilt about the human body and the parts involved with the sex act. These things, that then have names, or words, attached to them, are then supressed. When these suppressions, this religous overlay, are combined with business interests, they generally inhibit anything that might seem infractionary of these suppressions. Then, these names and words, and the ideas that are inherent with them, can't be used because they scare off potential customers. Also, if the corporations' sponsors pull their support, they'll lose whatever support THEY were giving and that could be a hefty chunk of change in some instances. So, they have to not only comform to their sponsors and what their guidelines and standards are, but they have to manage not to offend any of their consumer base at the same time. Reference that one guy from Gamespot who spoke his mind about the Kayne and Lynch game, then promptly got fired for it. That, in my belief, is the nexus that prohibits new ideas and their evolution and causes banality and mediocrity to thrive in its place.
Sony and Microsoft may be advancing more in this field than Nintendo, but they are still in the same boat as Nintendo. Occasionally, you will get some games that break this trend. Final Fantasy Tactics is a great example - religion intertwined with two warring governmental factions with all involved being exposed as some sort of criminal, save you who plays the main character, and the history of events as told by the narrator of the story reveals that the church covered up most of the events of the game after it happened. More often than not you will see dynamics of games change, graphics and the like, and HOW you play them, but the ideas behind them are relatively still the same old crap from 20+ years ago.
Kirby rocks Nintendo. The plumber brothers and the boomerang-toting elf boy have NOTHING on Kirby. Samus might, though. In the end, Kirby still wins.