The two licenses are for different purposes. The developer license is for the individual with clients. The other licensing is for an individual. There are a few with developer licensing due to the desire to contribute back code, make suggestions, help work through concepts and exchange ideas. There are a few with the license due to the large size of their site or unique features they want to add.
With that stated, I believe only a handful started out with the individual licensing and I manually moved them up to a developer. I don't foresee it being a store item.