8GB of GGDR5 RAM is an amazing move. Most games today don't use that much RAM because those games are mostly tied to the development of the 7th generation despite some PC games being more advanced, the new engines, and new graphic effects are hardly in use.
The high overhead in a typical PC also effects the graphical capabilities of a machine and most PCs can hardly squeeze the power of its set up compared to a console system with a low overhead and dedicated customized GPU/CPU; not to mention PC developers have a spec target to reach making a lot of PC games not as cutting edge as some might think.
You also need to take into account PC games, despite the ability to customize the graphics quality is built around a goal RAM so that they don't isolate themselves out to a small install base. The 8GB is going to be a big help to prevent the bottleneck of the GPU down the road, which the PS4 is relying on heavily for its graphics. It isn't necessary to have this much RAM, but if it had less it would strain developers, increasing costs and reducing the graphical capabilities which is a waste for the set up in the PS4.
The added costs is supposedly around $50, which is small for the return they get from it, much more successful later years of the system. In total the PS4 might cost $500 tops to build, package, and deliver to retailers. They will probably sell it for $400 and lose $100 on each unit. Compared to the $240+ they lost on the PS3 that is nothing, especially when you take into account they didn't spend a crazy amount of R&D developing technologies for the device. The hidden cost of the PS3 is far beyond the original $240+ loss a system. That isn't the case for the PS4. They could probably sell that thing for $200 and still lose less money. That would be crazy though for Sony right now and in general, just trying to show perspective.
Before the PS3 everyone was nice to me :(
