I think the direction of probes had more to do with where stuff is in the solar system. Due to rotation a massive percentage of what we would want to see lies in an essentially flat plane. Localized to the solar system of course. Outside of that it exist in a more 3D dispersion, but as we are incapable of sending anything fast enough to matter, we don't.

Using telescopes we do view it that way though. Sometimes at night I use my eyes & camera to do that too.