Given their history they would say, 16 GB is not enough.

It will reduce the size of the game on disk. You need to store all those unique trees, geometry and texture variations in memory first before rendering. It is too inefficient to generate them on the fly for each draw operation.

What kind of additional disk cache do consoles have? My task manager informs me that (next to 3.1GB in use) Windows is using 3.2GB standby memory, containing cached data and code that is not actively in use, plus another 148MB of modified memory that hasn't been written to disk yet. Start the same program a second time, it starts a lot faster, not so on consoles.
It's a lot more work to get your code to load efficiently on consoles without a big fat bloated memory manager backing you up.

No, optimisation is using all the resources effeciantly as possible. So naturally an optimised game will use all available RAM. Leaving unused RAM would mean it's unoptimised as it's leaving resources unused. Developers can alwayse use more of everything, you can never have too much there will alwayse be ways of using it.

I'd love it if they focused on making fun games rather than pretty ones, Crysis was a bore.

Sony and ms said games only use like 5 or 6 gigs not the full 8 gigs

That's one massive game where you're using that much RAM. I can assure you, most devs don't have the budget to make such power-hungry games. For example, if I were playing LittleBigPlanet on my PS4, what is gonna use up 8gb of RAM, unless they just fill it up with random garbage? Games that require such heavy use of RAM even after optimizing are far off for now, I assure you. 

Pre caching assets to avoid any loading, while also allowing much greater asset veriaty and much larger levels with more interaction. Just look at the Witness a game that uses mostly static inviroments with relatively simple assets, from an indie studio with a handful of employees. Yet it uses all available RAM on the PS4 already because they load as much of the game as possible so as to avoid load stutter while having a seamless game world. And they also do neat things like having hundreds of different sound samples for footsteps on every different meterial in the game so you don't get the usual repeating sound effects.

It doesn't require a big budget to use avaiable computing resources.

I can't see any contradiction here. They asked for 8 GB or more. Now they say they will use all easily. It definitely makes sense.

I'm guessing you didn't read anything.

He said the amount of RAM is going to be a limiting factor. That's something PS4 and X1 have an equal amount of, albeit faster on PS4.

This article is basically Crytek boasting of how easily they can use the full capabilities of these new consoles. But these consoles are still capable of plenty.

I'll take the word of someone who knows his shit rather than the guys who are famous for sucking at optimization.