I don't think the GPUs of PS4/720 will be able to push all that data at once. So I think the Ram will influence tons of things not directly related to graphics. Skyrim for example imagine no loadtimes imagine breaking through the windows of a house and soldiers on the streets running around infront of the house while you look out the broken window. Imagine more variation in textures.
More different types of Intelligence NPCs could have a more individualized AI. Depending on character race . More NPCs at once everything now can have more depth. Game design was mostly limited to 512-1gb Ram in the past. With 6-7gb Ram Developers now can change everything if they want to. Games now can start to try things that were previously not possible.
How is that able to be scaled down to a system with far less RAM?
They just can't be done. If the baseline rises you will need all that Ram to do certain things with it. Devs often can work around a Bottleneck but sometimes its an unsolvable problem.
Don't expect efficent use of all that Ram in the first years. But I am sure that soon games will need way more Ram than they used to because devs will try things that we haven't seen in the past. The gamedesign will be influenced by the huge amount of ram the next gen consoles will have. Developers wish always for more Ram because it means more freedom, I am very excited to see how games will change in the next years.
And this gets to the heart of my concern. Sure, the Wii U can do fighting games that will be on other consoles, but in other games, assuming Open World is the norm, I see you would have to get stuff like Black Ops: Declassified, which use the same IP as the other two consoles (and the PC), but a different animal, scaled back for the Wii U.