First the PC will have better specs on paper, but when it comes to running the actual game, the performance may be worse simply because having a console allows for more highly tuned and specialized code.
Yeeeah, not in this generation. That's because Sony and Microsoft went for 1.6GHz AMD Jaguar Fusion family of x86-64/GPU processors instead of custom processors this time around.
Second, that $600 PC purchased now will definitely be a lot better, but if it were purchased at the time of release, even the raw numbers wouldn't be all that much better, never mind the actual performance.
The consoles use faster RAM (actually, only the framebuffer does for the XbOne), but the PC's clock speed advantage is likely enough to close those gaps... and is pretty much guaranteed if they use a dedicated graphics card (as the RAM speed advantage largely goes away in that case).
Also if you don't already have a good monitor, that's even more of an investment, unless you want to hook up the PC to your TV as well.
If you were doing a Gaming PC, this is exactly what you'd do.
That's one nice thing about everything using HDMI cables these days.
Third, you forget the a console gamer can buy used games at a store, whereas PC gamers typically can't resell their digital downloads. Given that the online digital games on sale will probably be in the same price range as a used disc in a store for a similarly aged game and it's not that big of a difference. If you want to play the newest games as they're released the full-price cost is going to be about the same whether or not it's on PC or console.
Yeah... that's not usually the case. Steam sales tend to be cheaper than used copies of console games. And sooner in a game's lifetime as well.
However, there are some people for whom a console is a much better value proposition. If the PC was hands down better in every case, no one would buy one. However, given their popularity, it seems to suggest that there are a large number of people for who consider a console to be a better value.
Consoles are largely easier to set up and use.
This is the kind of thing that the SteamBox standard was created to fight. However, then Valve started mucking around with the "standard" before the first one was even released. Heck, I still don't think the controller has been standardized and SteamBoxes were announced like a year ago!