system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come the development cost of the next generation console games is supposedly so high when there are already the PC versions that look better than anything next generation on consoles?

Something like Metro Last Light looks absolutely amazing on PC, significantly better than anything we've seen from the next generation, yet the development costs were quite low. Now that the next generation of consoles is merely catching up, how come the work is quadrupled (according to Killzone devs anyway)? So far, everything is as linear as ever, the AI is the same as ever and quite honestly everything seems like the PC versions of current generation games. So, how come the development costs are suddenly that much higher? What is changing?
gpt
Okay I'll take this question by question.

>How come the development cost of the next generation console games is supposedly so high [...]

Because licensing, publishing to console costs around 300-500k on the part of the studio making the game in order to get access to the 'secret sauce' things that the company making the console uses. 

 >[...]when there are already the PC versions that look better than anything next generation on consoles?

Hardware. Consoles can't sell at the price of 800-1500 dollars. Which you would need if you wanted to compete straight up with a high end gaming PC because the hardware is more complex and powerful.

Also power. A typically gaming PC draws upwards of 700 watts of power, while a Console typically draws ~250 to reduce noise/cooling. Power is a big barrier in performance and you really can't turn on a computer with a high end GPU on 250 watts of power.

>Now that the next generation of consoles is merely catching up, how come the work is quadrupled (according to Killzone devs anyway)?

They need to relearn what they already know. For example "println" may do something completely different and "printy" may do what "println" used to which increases development time and costs.

On top of this rumors are that XboxOne and PS4 maybe using the AMD's MantisAPI internally instead of OpenGL/D3D/DirectX. Which is far lower level, the reason why the later 3 were invented was to cut on development time that 3D systems like Glide/Mantis created by being so much lower level, and having to re-do a lot of code often for simple things instead of libraries taking care of it for you. This is naturally at the cost of higher performance (simpler API slower it works, generally). 

>What is changing?

Nothing, its just natural progress. Gaming systems have to get more complex because their consumers demand it, in order to stay in step internal coding has to get 'closer to the metal' in order to let developers squeeze every ounce of performance out of the system they can.