Something that I don't think was covered, adding a penalty for unskilled checks kinda screws you over for char generation. The basic implication when building a character is that starting out the challenges are such that you don't need to be trained in a skill to succeed. Thus you can put most of your points into attributes since you won't be raising them often later. Once you add a penalty then you pretty much either screw the guy who bought attributes over skills or screw the guy who doesn't want a penalty so invest in skills at the cost of not having good attributes.
That isn't to say that there aren't task that maybe one should be skilled at before performing, but that's kinda what the black dice are for. But the game inherently assumes that early challenges are more along the lines of things that can be accomplished without needing skill ranks. Penalties disrupt this basic assumption in char generation.
Except you do need to be trained in Planetary Pilot to even use a jetpack. So the concept of specific Skill ranks that represent a higher degree of required training to even attempt something is a layer of granularity that is included RAW in that example.
I think a GM wanting to add things along that line is well within the bounds of acceptable thinking, plus if houserules are laid out at CHARGEN no one is screwed. They're simply presented with additional house rule prereqs.