*sigh* These arguments are as old as the existence of computer and console games themselves, and though I know it's not helping anything for me to post to this, I'll have a go.
The gaming market nowadays has moved from its long-time place as a niche or tech-based arena to being a much more mainstream pursuit. This is due partially to the fact that gaming is such an easy hobby to get into, with many gaming-capable electronics being considered necessary for many people's day to day lives to begin with, and partially with the original so-called "gamers" now reaching the middle parts of their lives, having in the process passed their gaming hobby on to their own children, and in some cases even their children's children.
This, of course, has some side-effects. Rather than being an industry where simply making some form of profit is seen as a positive while producing games for intellectual reasons, like many of the early titles were produced for, it is now a multi-billion dollar industry that has permeated every perceivable area of modern culture. Games are so readily available that a small upstart cannot as easily make a name for themself with a small title that proves their technical ability and creative ideas, but must make something that either appeals to a large audience, or has the funding to effectively draw the attention of what market it does appeal to.
Because of these elements, it is vitally important to the survival of most game production companies that their titles span the largest audience possible. The more advanced the technology grows the more talent is needed to produce titles that take advantage of it, and while there is a decent portion of that community that appreciates games based on their merits as games rather than technology demonstrations or mass appeal, they do not make up the majority of the community that game developers are now forced to market toward if they wish to make a profit.
Whether you hate them or love them, consoles make up a significant portion of the gaming market, and as such catering to the crowd that has invested in them is in the interest of game companies. In many ways, such catering is more profitable than if they were to focus on the PC market as consoles are comparatively cheaper to develop for due to their more stable hardware and lesser variation in structure.
With the ever-increasing similarities between the technology used in current-gen gaming consoles and computers, cross-platform titles have become much easier to produce, but are still significantly more expensive than in prior generations due to the amount of work needed to use the tech effectively. As such, fiscally-minded corporate executives will tend to find it in their company's best interests to aim their products toward a lowest-common-denominator in order to maximize the income from all investments. In this case, that means primarily designing games for consoles, and summarily porting them to the PC.
For production companies this works wonders, as with the ease of porting between Microsoft's current console and its DirectX frameowork on PC they can design the game once and essentially have twice the market for it, a state which will only grow more pronounced with the development of cross-platform PC/console development tools, such as XNA. The downside is the chance of alienating a portion of the PC market by not taking advantage of the advancements in that technology beyond what the consoles can produce, but generally these losses will be small in comparison to the audience that can be had by appealing to a broader hardware profile.
On top of all of this, the PC gaming audience has greater access to game piracy. While the argument against DRM still applies, it is nevertheless an accurate assumption to make that the corporate offices that handle financing for titles are going to be less interested in funding advancement in an arena that they see as offering little return on their investment when it crosses a certain threshold of ease/cost versus noticeable results.
Why can't a company make a smaller budget hardcore RPG maybe in 2d and with less voice acting for a more hardcore crowd. Fallout one for instance only had a few people working on it and I don't think cost that much to make compared to newer titles. Even if this idea for games sells a lot less it could still make a profit... It seems to me that movie companies do similar things by sometimes making or producing a smaller indie film that may make less profit but cost less money to make in the first place. I posted something like this in another topic. I'm not sure how stupid my idea is....
addendum- maybe wrong about fallout one seems like it had some prominent voice actors... but it seemed from this one interview it was mostly what a few people did left by themselves. . also, maybe it was just the early stages of the designing of fallout one only a few people were working on it. oh wellz.