It is the best thing because it makes Linux so easy to install and get started with on Windows PCs which dominate the market.
It is the worst thing because desktop Linux users are no longer forced to dogfood and fix laptop hardware issues, and so these issues will continue to go unfixed, and native desktop Linux installs will thus continue to suffer.
Case in point: I've used desktop Linux for more than 20 years and I recently moved to using WSL on Windows because I love having all my hardware devices like my photo printer "just work" on Windows and I love getting great laptop battery life.
It looks like the Thinkpad X1 Carbon is the only killer laptop you can buy with Linux preinstalled that has a 4K UHD screen option, but Lenovo makes the buying experience extremely frustrating. Lenovo overprices Thinkpads most of the year and then occasionally does killer sales. And Lenovo has lately been suffering 4 month shipping delays on many Thinkpad configurations. I'm sick of wasting time waiting for the sales and then trying to buy before the reseller bots buy up the deals. So I bought a non-Thinkpad Win 10 laptop instead and I run WSL on it for my Linux needs.