I think it would be far worse if we stopped developing new hardware. The focus on mobile devices, and battery life in particular, has done a tremendous amount

I think it would be far worse if we stopped developing new hardware. The focus on mobile devices, and battery life in particular, has done a tremendous amount to reduce power consumption. A typical desktop computer from the 2000s could easily use 1000w. Some of the pentium 4 variants burn through more than 100w alone - not including any of the rest of the hardware in the machine, or the monitor. A modern laptop will usually come in under 50w - and can usually idle down under 10w. Servers 20 years ago were mostly big power hungry machines running in closets somewhere - now they're heavily power optimized machines running in AWS/Azure/GCP/Other's data centers. CPU cycles have gotten ridiculously cheap (both monetarily and in terms of power usage). Single-threaded performance hasn't gotten all that much better. The market is already optimizing for reducing power usage, because power isn't free and because batteries are a constraining factor in mobile devices.