*Of course* you can earn money in different ways with an NP. That's
not the issue. The issue is that spending the NP for Common Magic is
far and away the best tactic for earning money.
Even your "hire an extra noble and have him sit in an inn" example
doesn't hold water, because you must spend the extra time and
resources to build the inn, your income source is tied to a particular
location, and you only make about 60% of what common magic makes. And
I think the inn is the best counterexample.
(And I'll also point out that you don't spend the NP to learn "Perform
Common Magic". You spend it to learn Basic Magic. That NP point also
permits you to learn a bunch of other skills.)
>Anyway, as I'm sure Rich knows, I and many other people would strongly
>object if my nobles end up in the middle of nowhere, and then their
>planned source of income suddenly gets cut off.
Your earlier post implied that you had reasons for believing that
Common Magic is balanced. If your objection is that it will throw off
your game plans, that's something else entirely. Presumably Rich will
scale in the change, or do something else to make the changeover
I'm of the opinion that if one skill is providing almost half the gold
that is entering the game, and that using the skill requires virtually
no resources, then that is a serious problem. At any rate, it clearly
shows that most people agree with my assertion that common magic is
the easiest and best way to make money in the game.
If you really believe otherwise, I invite you again to compare common
magic to  inns,  temples, and  trading.
-- Scott T.