Previous investment in Windows architecture for one. Cross operability with locally running Windows applications for another. Unfortunately though there are obvious solutions to these problems, those who make decisions about spending are often not as concerned about doing it right (IE they already invested in Windows). It's a selling point for adoption. I suspected that with Linux Shell in future Windows Servers Kitura will just run there, but I'm sure there will be performance hiccups doing that (at least compared to native environments).