You may have missed the real world benchmarks which show that that last .5Gb of the 4Gb is not a performance bottleneck in a real world scenario. It hits only a certain benchmark which saturates 100% of VRAM on every run and that's not what games do.
The 970 is the price/performance leader despite the confusion with the specs.
Actually, it does hit in the real world, if you are running resolutions higher than 1920x1080 with any anti-aliasing and large (4Kx4K) textures (most games released in the last couple of years have those). When it hits in a game, you know about it as performance tanks.
It makes sense as to how NVidia got the price so low to start with. Cheaper low speed ram, fewer than advertised ROP's, less level 2 cache than advertised as well. At least they were honest about the memory path size (256).
NVidia did not do themselves any favors by being deceitful about the specifications. When a company does that, it says they are not confident in the product.
One thing for certain, it gave AMD/ATI a windfall in sales. Dumb move. I was looking at getting a 970 myself, until this broke. I run higher resolutions, with anti-aliasing a lot. I am not going to gamble I will hit that performance wall. I'll just wait a bit because the AMD offering runs way too hot (i.e. consumes too much power) for my tastes.