Yes, a lot of people have that perception, but although that was certainly a desired effect of the project, it wasn't the primary purpose. The main purpose was a much more pragmatic one.
Back before [3D content creation suite]Blender was open source, it started off as an in-house application used by a Dutch animation studio named NeoGeo (founded by Ton Roosendaal, one of the original programmers of Blender and also chairman of the Blender Foundation). One thing that Ton really missed from those days was the directed feedback and development that you get when working on a project with artists who have real problems to solve and real deadlines to meet.
So rather than doing Elephants Dream to show you can make a quality short film with open source graphics software, the idea was more about trying to make a short film, and along the way identifying the roadblocks, and doing the required software development to make it possible to do a short film with open source. By doing a practical project, we could find out what needed to be fixed, what extra features were needed, and how we could improve workflow for doing practical production work.
Of course, being a showcase for open source was a nice part of it, and the fact that we actually succeeded in finishing the movie (phew!) is a great validation for the process. It was due to a lot of hard work, but it's not just about slapping each other on the back.
As to whether it succeeded, in the showcase sense, I think it surely has raised people's perception of Blender. A lot of people unfortunately equate free with worthless, but in the arts industry, having a good 'portfolio piece' makes a lot of difference to changing that perception. It's most definitely succeeded in the practical sense too. With the tool set we had available at the beginning of the project, we wouldn't have been able to do what we did, and the project has done wonders for making Blender a much more bulletproof production tool.