Are you joking? Check the changelog of the open-source version. http://nginx.org/en/CHANGES

It's a common question. As you correctly noted in the changelog, the vast majority of features have been placed in the open source version. The commercial product has gained great visibility and adoption but open source NGINX is very core to our company. In fact, development and feature releases to open source NGINX have rapidly increased since the inception of NGINX, Inc (the company) because it can support the development efforts :)

(disclaimer: I work at NGINX.)

Just maintaining a project as large as nginx is hard enough, and takes a lot of people to do it.