I can't see a reason to run a VGA cable today...but it's the unknown future which might be a reason to drop a cable in there.
For example, you may someday need some extra "Source Areas" (these are the settings unique to each input). One way to get some more would be to run a 5 BNC to VGA cable from the Rock into Computer1. Then you could switch to the Computer1 input (if needed someday) and have a bunch of new source areas.
Again, I don't think that you will need it for a while (until you run out of source areas on Computer2), but possibly in the future...?
Technical Director, Home Theater Products