I question this study's sample size and diversity.

Git was made by and made for kernel hackers to support the Linux kernel. It has an expectation that the user understands how their computer works and wants a tool catered to that knowledge. The average web developer writing Ruby or Node in Atom on their Macbook Pro isn't in the target audienece. For someone in git's target audienece, it's a great tool with far better UX than any other VCS - because it gets out of your way and gives you powerful tools for mucking with the VCS to suit your needs precisely. THIS is what makes for a good UX. A tool that's easy to learn is great, but if it can't be mastered and bent to the user's will then I'd rather take one that's hard to learn but accomodating of the master.