I don't think it's dumbed down as in intelectually. Mostly I use it about control schemes, which is the main drawback of the consoles. You can never achieve the same amount of different keys available on a console as you have on the PC, and so when you take a game and it uses "context sensisitve" control schemes, you can pretty much assume it was made to and ported from a console. That don't sit well with me; I have a million keys, six keys on my mouse, yet pressing E does everything? Why not use Q, R, T, V, X, C, Z, F, V, G...
Mostly I blame publishers who don't take the time to reconfigure the control scheme of a game to make it natural for the PC. A game like Borderlands, which I've played a lot, has horrible controls, and it's obvious it was made for a console. Using something will reload your gun, and you can't reconfigure it so that you reload exclusively on R instead. That's bad. And driving a car is W,S for movement and the mouse steers. You can't, as in most other games with cars (UT 2k4/UT 3 springs to mind here) look at the side of your car while moving forward, which makes for terrible driving sequenses. And when an entire DLC is all ABOUT driving (I'm looking at you, Knoxx), it becomes nigh intolerable.
Call me a bigot and an asshole, but I truly believe that the PC is superior to the console, also in terms of gameplay. Again, it's got nothing to do with maturity or intelect as OP suggests, rather, it's the limitations on consoles that means making stuff less grandiose. I seem to remember a game like TF2, where VALVe simply had to stop delivering content to it, because the content by now has grown so large it will barely fit on the console in regards of what is allocated to each game (and microsoft wanting pay, bla bla all that). When you have to limit your game because of space, even if it's just a little bit of limitation, you're still making an insufficient product compared to what you could (and should) make for the PC.
PC users aren't a "master race", and we don't percieve ourselves that way. Sure, some people do, but there are idiots in every single group and culture. I don't condemn people for using consoles; They're easier and more practical, and if you don't want the hassle of having to update drivers, upgrade your system and pay out the ass for it, I totally understand that. However, I still think people should be open about and accept that fact that ultimately, PCs are more capable than consoles. So far. Let's see what the future brings.