That's an aspect of it I hadn't thought through (Emphasis added):
You need 6 ranks and 6 PP and have the scaling penalty and the time issue.
The casting penalty for armor
can't be
just a negative for time, and rolls
...because you get that
anyway by using the extra PPs on the spell, whether you're wearing armor or not. And of course, you have to have as many ranks in a spell at minimum as the number of PPs you intend to spend casting it.
If you cast a spell with a base cost of 4 PPs, and spend an extra 2 PPs
on whatever, you get the scaling penalty to the roll and the extra time needed to cast it. This holds whether you are buck naked, wearing full plate, cast in concrete, etc. That being the case, what part of a "casting penalty" of 2 PPs actually qualifies as a penalty
that you wouldn't otherwise have? The only thing available in the mechanics that armor can add to the burden of casting the spell is to add to that minimum required, because the other penalties are already in place
regardless of why you needed the extra PPs.Does that make sense?