I also like the idea of a preconfigured SD card, but I would also like to keep openHAB independent of any specific hardware and support the different platforms equally well. That’s why putting a lot of effort specifically in a RaspPi image is not on OUR list, but it would of course be very welcomed if being done by the community. The scripts that @peter mention sound like a good starting point.
In general, I am rather looking at things like Docker container or Snappy apps; if we had such images automatically built, this could be used on many platforms; so we could have an RaspPi SD card image, which simply includes the Docker container in it. This might be the best way forward.