Performance per watt is something no one cares about. Laptops are a tiny market compared to servers. I'm pretty sure desktops are even a larger market. I'd rather have a beefy desktop PC than a laptop that's fundamentally handicapped by cooling problems.
The only people who don't care about performance per Watt are those who have only one computer with a handful of cores and it is running off mains power.
People running from batteries care a lot about performance per Watt.
So do people running thousands or tens of thousands of computers in a warehouse. Not only does the electricity to run the computers cost more than the computers themselves, but it also costs a lot of money to build and run the cooling systems.
