Well, that's not surprising. The video games industry has changed a lot over the years. No longer are video games sort of just a "hobbyist" thing. The market has grown and expanded by huge amounts. A lot of it probably started with the Playstation 1, which is when an "outside" company tried to get in on the ever-growing video game craze for the first time. They decided to market themselves towards a more "grown up" and "more serious" tone, which indeed did shake things up a bit.
Sure it still had its share fair of quirky stuff, like the GOOD and ORIGINAL "Spyro the Dragon" games and "Crash Bandicoot" (back when he was bearable) and even Parappa the Rappa. But still, it opened a whole new world of people to market towards, one where loads of money could be made relatively quickly.
Then you have the last generation, where things became even more polarized, what with the Xbox being deemed a mega behemoth hardcore piece of machinery for big tough manly men, and the Gamecube being considered a toy for kiddies, and the Playstation 2 kind of trying to balance itself between the 2. Though the Playstation 2 kind of stunk for the most part, until near the end of its life with Okami I think, and some other cool stuff.
But alas, the industry was growing, and of course, video games are a business. And like any business, they make what will sell. And seeing as how the big gray brown tough FPS's and stuff like it were doing well (especially with popular stuff like Halo coming around), the industry wanted to milk it for all its worth, like any business nowadays would.
And now, here we are, at what is quite possibly THE most polarized generation of games ever. The Playstation 3 couldn't get anymore behemoth-like, the Xbox 360 couldn't fit anymore guns into its rack, or anymore Online-dependant games in its library, and the Wii couldn't be more "baby-ish/family oriented", and that stuff is expanding the market even more, thus making the entire industry even MORE mainstream.
Game systems before used to have loads of variety in their libraries. Yeah, they all had their specialties, but still, there was plenty of variety and fun to be had no matter what system you chose. But not now, though. Its all become so heavily polarized and niche driven that any sort of really variety or experimentation is due to sell far less (thanks to people being the scared, close minded sheep that they are). And this stupid "Hardcore/Casual" thing isn't helping. And considering that games are now a big, multibillion dollar mainstream business, and also considering that games take so much money and time and work to produce, there's no room for bad sales. Money is their first priority, not making good games. If motion sensors and waggle fests and brown/gray macho manly 5 hour =long Halo rip offs are what's selling, then that's what is going to be made.
Really, we only have ourselves (as a whole, not anyone in particular) to blame. They serve us a giant pile o' poo on a silver platter, and we buy it, so they're going to keep making it, and thus the cycle continues...
But don't take my word for it!