The argument for price isn't a great one...
Yes, at a base level, a next gen console is marginally cheaper than what you could build an equivalent spec PC for, but if you're prepared to put a bit of work into speccing up a build, you're only talking about £100-150 more for a similarly performing PC. Once you take into account the cost of games, unless you only buy maybe 1-2 games/year, the price difference disappears within months.
I cba to find it, but there was another thread about this, just when the consoles were released, and someone posted a PC spec which was pretty much on a par with the PS4/Xbone for only ~£50 more; given the constant advance of tech, I would imagine you could get similarly close today.
If you're going to use cost as an argument and keep stating how relevant it is, then it's disingenuous to then disregard the cost of the games (since any gaming system is going to be pretty useless without them).
Purely my personal example, and of course others will probably have differing experiences, but I spent more on PS3 games in the 3 years of owning one than I have on PC games since I started gaming in 1997.
Just some examples from Amazon (All rounded up to the nearest £):
Shadow of Mordor (30% cheaper on PC):
PS4 - £37
XB1 - £37
PC - £25
The Evil Within (40% cheaper on PC)
PS4 - £42
XB1 - £40
PC - £25
Alien Isolation (10% cheaper on PC)
PS4 - £37
XB1 - £40
PC - £32
NBA2K15 (10% cheaper on PC)
PS4 - £44
XB1 - £44
PC - £40
Lords of the Fallen (40% cheaper on PC)
PS4 - £42
XB1 - £42
PC - £25
Assassin's Creed Unity (11% cheaper on PC)
PS4 - £45
XB1 - £45
PC - £40
COD:AW (4-5% cheaper on PC)
PS4 - £42
XB1 - £42
PC - £40
FC4 (10% cheaper on PC)
PS4 - £44
XB1 - £44
PC - £40
Some of those differences are ridiculous, and if you buy smart (e.g. in Steam sales) then they can be even cheaper, however, an average of 20% cheaper for PC games is not to be ignored.
There's also the fact that many households have a PC anyway, as one is needed for other use, so instead of having a £2-300 PC and a £350 console, you have a £4-500 PC capable of doing both (although granted this is now reducing due to more people using tablets etc).
There's also the fact that when you buy a new console you suddenly have no games, buy a new PC, install Steam/Origin/etc, and you still have a huge back-catalog - I've recently ditched my PS3 (well, actually I still have it for use as a BR player
). At the time, I had the choice of a PS4 or a PC for similar cost. I ended up going for the PC, as what I could get second hand was
far superior to what the PS4 could offer*, not to mention having access to all of my Steam games (and lovely low prices for all the PC games that I'd not played for the last couple of years). If I'd bought a PS4, I would have then had to also pay at least another £30-40 just for one game to play on it!
By all means, consoles have their place - so much easier to just turn on, and veg out on the sofa without having to faff with drivers, settings, installation, etc. but the cost/performance argument is a very weak one when
everything is taken into account.
*I ended up with an i5-2500/16GB RAM/128GB SSD/2TB HDD/GTX 750ti OC, which cost me a total of £350, this was when the PS4 was still £400+