Open source is no different than any project or business. Marketing matters. Design matters. Name / Brand matters.<p>We (engineers) do ourselves a disservice by dismissing the 'soft' parts of gaining mindshare.<p>There are a bunch of image loaders on Android. My personal technical preference may be Android-Universal-Image-Loader, but it sure is a heck of a lot easier to tell people to download Picasso. And when they google 'Android Picasso', they are going to land on Square's awesome landing page for it. It's not a coincidence that it has become one of the most popular options.
Unfortunately, the motto: "if you build it, they will come" mentality loved by engineers/developers, who love creating and hate selling, is not a thing.