It is. The biggest benefit for consumer devices is less lanes needed for same bandwith, but that is only really relevant to GPU's. SSD's are already constrained by thermals, not bandwith.

The downside - cost. Making these lanes run reliably at these speeds is not cheap.

I wouls say benefits for consumer devices peaked at pcie 4, anything above is just cost. Maybe gen 5 to allow gpus to run at x8 without bottlenecks, but given how massive those gpus are, you are not saving any space, just lanes.