HA, my situation was similar, but I 100% blame it on nvidia nv drivers was causing endless driver crashes and occasional blue screen of death for my 460 1gb. I went for a 660 ti. than I upgraded to a 280x. 3 months later I got a 290 I lost 20 to 40% resale value on the in between cards. 460 1gb is still in my sister's pc with a very very old working driver(it is probably now almost 3 years old). almost upgraded again this gen till I saw the crap benchmarks.Stagnation is game development due to consoles. Mobile gaming becoming huge. 1080p being a standard for a decade. It all adds up to hardware on the low end is probably doing a well enough job people dont need a dedicated GPU. The games I play still work fine on a GTX 470. These games arent horrible looking games neither. (Warthunder, World of Warships, Diablo 3, Cities XL).
I upgraded because of hardware failure(AMD 5870 died, sold the 470, bought a 660 for the kid, 770 for myself). If that 5870 didnt die 20 months ago we would still be rocking those cards today.
all that trouble because of crap nv drivers.