Hard drive development hasn't stopped. It just changed direction, because pursuing better seek times is pointless when it is impossible to increase RPMs enough

Hard drive development hasn't stopped. It just changed direction, because pursuing better seek times is pointless when it is impossible to increase RPMs enough to catch up to even low-end SSDs. Perpendicular magnetic recording hit the market around the same time SSDs started to go mainstream. Since then, hard drives have advanced with the introduction of helium filled drives, multi-stage actuators and shingled magnetic recording. This has enabled an order of magnitude increase in drive capacity, and substantial increases in sequential transfer speed. Dual-actuator drives and HAMR/MAMR are in the process of moving from the lab to commercialization, and will respectively bring an increase in random and sequential IO throughput (but not latency) and more density increases (which always bring some sequential throughput improvement, too). What's really been missing from the hard drive R&D scene is more Nobel-class discoveries like giant magnetoresistance to allow for big jumps forward.