the thing is with consoles is that they are a closed box and all the same, which means that games are developed specifically for the console hardware and take advantage of every bit of power they can muster.
for example I have a windows gaming laptop that is quad core i7 with 8 threads, 32B of DDR3 memory and a GTX675M GPU, when I run a game it hardly uses any of my 32GB of ram and I get very little extra processing power from having 8 processor threads compared to if I just had 3-4, the game is designed so it's compatible with a wide range of hardware - not my specific setup.
also on my laptop I'm running a bulky OS and virus checker and a while bunch of other stuff a console does not have to deal with.
That means that the actual on screen performance from a console is much much better than a PC of compatible specs.
Where a PC game doesn't make full use of my laptop hardware a PS4 game will take full use of the 8 CPU cores, all the GPU cores and all 8GB DDR5
so even though the "next gen" consoles are far behind what a top of the line PC can do the actual performance will be really impressive
also consider cost, I mean a top of the line graphics card for a PC is $800-$1800 just for the card
sure sony/MS could have gone more powerful to cutting edge but that would have pushed the cost of the console to 2,3,4x what they are going to be. Sony kinda did that with the PS3 which was ~$1200? when it came out, that ended up being a big mistake and the PS3 only really took off when they found ways to drive production costs down, I think they even lost money on console sales.
The other limiting factor is the TV. I mean whats the point in having GTX ***an power when the standard resolution of TV's these days is 1080p
I think sony have got it spot on, their product should have fantastic power for really impressive 1080p gaming at a reasonable price point and be easy to develop for. the new xbox not quite as good or as powerful and will cost a bit more but it wont be to far off and still much better than current gen consoles.