yes it could do 4k in AAA games. Look at MGS5 its 1080p60fps it could run it at 30fps in 4k on PS4. Its not supported by Sony tough because they know most people dont have 4k monitors.

Yes more videoram on graphicscards gives more performance on higher resolutions. A Graphicscard with more videoram performs the same like a graphicscard of the same model which has lower videoram @the same settings in PC games. But ounce you start increasing the resolution in a PC game, the graphicscard with the higher videoram is performing a lot better than the one with the lower videoram even if both are the same models.

Given that the PS4 and Xbox One are using unified Ram architecture and both are APUs, increasing the ram on these consoles would increase the performance or allow for higher resolutions in videogames.

Yes, because 4k only doubles the rendering load.

Seriously, you get so many things so wrong on so many levels, please educate yourself next time before you post something instead of just saying something that you only think might be true.

*sigh* 

Highly doubt it could do 30fps in 4K at the same settings since shading performance would become a limiting factor. 4k IS supported on the PS4 and there's no reason to believe it can't output 4K & 30fps games either since it's HDMI port is capable of doing so ...

More video memory only improves performance if and only if your video memory limited ...

Your last statement makes absolutely no sense ...

Question:
Why more RAM?

Saturn: Basically used the added RAM for animatons in 2D games as i remember. That's because you have to save every single animation phase as a picture for bitmap graphics. And that eats up memory.

N64: was a bit short on memory. That's actually because of some of the system features like higher color depth, mor alpha channels and other stuff. Now most games use the expansion pack for higher resolutions or higher res textures..., very few, AFAIR just three games had it as a mandatory. Those games again used it where the basic system RAM was a bit short.

Thing is, both PS4 and Xbone and even Wii U have more than enough RAM. While RAM in the N64 was a limiting factor both current gen consoles have all RAM they need. Especially the graphics side has more than enough.

Developers would still have to make games for the least powerful systems of people who don't upgrade... so why bother? Over time, changes to the OS will help the systems run anyway and by the time you'd need to upgrade to make a difference, the next gen of consoles will be out.

Well in terms of storage, there are options. But consoles should be spared and they simply cannot keep up with how gaming PCs are meant to perform with upgrades.

Why? When adding a cloud ☁ would do the same. Use base specs for the game. Then add extra if clouding. Xbone for example: Make a game with stick figures. Then when adding some real power from Care Bear 🐻 land, make it PS4 level.

My beliefs exactly. I do see a ram expansion being able to add things like a longer draw distance because you can dump more on to them. 

God no, there's absolutely no need for that.

I think not. Memory expansion defeats the purpose of dedicated machines. Consoles have a lot of the gaming market because they encapsulate the necessary components for gameplay, eliminating the need for the average consumer to be bothered with upgrading hardware specs.