The idea was to provide static skills that could be useful beyond just 'being a profession'. Scribe can be used to create scrolls and similar magical items, so it's potentially useful all the way to level 20 for any caster, and I felt it would be nice and thematic for any Pathfinder. (Plus, they still get the bonus PFS trait.) Profession (soldier) is a little bit less useful, but I was planning on using the optional rules from Ultimate Campaign, where every 5 ranks in that skill gives a +1 bonus on a General's leadership modifier for Kingdom building. Hopefully, anyone choosing a trait giving one of these free skills would be interested in the skill for the whole game, and if not... well, it costs them nothing and isn't the only bonus they get from their trait.