As others have mentioned, I think you might be looking at one specific situation, interpreting it in a certain way, and applying your interpretation across all of PC gaming.
For one thing, high-end GPUs do not become obsolete in 2 years. I have a system at home with an old Core 2 Quad 9450 CPU and a GTX 670 GPU that can still run most modern games at detail levels that surpass current-generation consoles. The video card is 3 years old, and will likely continue to see use for at least another 2-3 years.
Also, game detail settings are relative. "Ultra" settings in one game can have very different hardware requirements than "Ultra" settings in another game. Case in point: when Crytek released the first Crysis game for PCs, there was a lot of belly-aching from people with expensive hardware that couldn't run the game at 60 FPS at maximum detail settings. They felt that because they could run other games at maximum detail settings, they should be able to run all games at maximum detail settings. This was silly, because Crytek intentionally released their game with detail settings available that were beyond the current generation of hardware. The idea was that as hardware got better, their game would look better. It was a way to add technical longevity to their game. People were so used to the relationship between hardware requirements and hardware being flipped in the other direction that they couldn't wrap their heads around the fact that Crytek had intentionally inverted the relationship.
I guess what I'm trying to say is that the fact that detail settings exist in a game doesn't automatically mean that you need to use those settings (or should expect your hardware to be up to the task) in order to get the experience expected by the developers of the game...much less to get an experience that's on-par with current-gen console hardware. Sometimes developers include forward-looking detail settings that are more appropriate for hardware that doesn't exist yet (or to accommodate people with bleeding-edge hardware that want to get something out of it.)
Combine that with Ubisoft's reputation for poorly-optimized PC ports, and I think you might be overreacting a little to the 8GB video RAM recommendation by Ubisoft.
Me too. In fact, I remember when I worked at Babbage's and Electronics Boutique was our main competition in the mall. Heck, I remember when the first Electronics Boutique stores started popping up in Illinois.