It has been this way for five years because many games are developed with portability in mind with current gen console in mind as lower target
As soon as the next gen console is here, expect the low system requirement to rise dramatically as optimizations are a real cost in game development.
I... pretty significantly doubt that. Minimum reqs will only go up as the general low end systems improve and become ubiquitous, not as the upper limit stuff increases notably. Otherwise you're cutting out a pretty major chunk of your potential market, since people tend to hang on to computers longer than they do consoles, or often aren't running dedicated gaming rigs. Relatively low minimum specs means a solid market increase.
In any case, one major advantage I've had with PCs is, well,
forward compatibility. Five years down the line, I might not still be able to run stuff at max graphics, but there's a
really good chance it'll still be runnable at medium or low settings. For a console, forward compatibility basically doesn't exist. I can't stick a PS3 disc into a PS2 and have it work. I
can stick quite a few PC games made in 2006 into computers made in 2000 and have them work. Perhaps not perfectly or at max quality, but it'll still do a pretty drat good job of functioning. And I can reasonably expect a top-tier computer now to still be able to play whatever comes out two or three console cycles from now.
Still, it's not impossible that we see an upward shift when crossplatform development doesn't have as heavy a console yoke around its neck. Be interesting to see.