Each upgrade makes it harder to make a chip IP/motherboard that is in spec due to the increasing frequency and signal integrity requirements. There's a reason

Each upgrade makes it harder to make a chip IP/motherboard that is in spec due to the increasing frequency and signal integrity requirements. There's a reason gen4 took so long to roll out - it has been finalized for 4 years (with he manufacturers working on support for much longer), and it's still not ubiquitous. I'm sure you'd rather have a gen4 or gen5 board when gen6 is rather than be stuck on gen3. (Plus, for gaming loads there are diminishing returns - outside reducing texture upload times, GPUs in gaming scenarios do not use a lot of PCIe bandwidth.)