Arioch,
That is another option of lettiing the first rank give you +15 for each of the Cat and Skill (RMSS), +30 total. I was thinking of a little smother curve to the graph with it only going up +20 [total] or +10 for each of the ranks.
I think it's a matter of intepretation of the "meaning" of ranks:
I see rank zero as "never studied the subject/have only a vague idea of what it's about" (for example I know that quantuum physics is a science about very small things: I have 0 ranks in it).
OTOH rank one means that the character has studied the subject for a while and know some basic notions about it (if I'd go to school and take some months of lessons about quantuum physics and read basic manuals about it, I would gain 1 rank in it).
Chance of success for actions in which you have zero ranks (assuming a total of +0 from stats) are almost non-existant: only by sheer luck (open ended roll) you can succeed in them and there is a good chance that you'll get a bad failure result.
With 1 rank your chances of success are very small (and you're probably going to get only "partial successes" in all but the simplest tasks), which is still a lot better than no chances at all.
IMHO this is a good reflection of the fact that with no ranks I don't know anything about the skill and with one I know only basic informations.
My thinking is to force players to spend a little more DP's in other places than the standard areas.
IMHO if you want players to buy "non standard" skills, lowering the bonus for rank one is not a good solution: it would only make them spend more DPs on "standard" skills, to be more effective in them, and none in the others.
Maybe you should force them to spend at least a certain % of their DPs in non-combat/non-spell skills, or make the progression of certain skil dependant on others (for example, you cannot have more than 5 ranks in broadsword if you don't have at least 3 ranks in Lore: Combat Styles or you cannot have more ranks in Fire Law than your ranks in Lore: Elemental Planes, and so on)