While i think this could be good news for Bitcoin, lets not get too far ahead of ourselves.
This is a great use of Bitcoin - making a payment that is normally a one-way payment; people don't chargeback their tax payments, and only the absolute rarest will put a stop payment on a check. Bitcoin fits in perfectly for that. More and more, tax payments are e-Payments, and with each payment going to a unique address, verifying that a payment was received on such and such a date would be trivial.
It doesn't signal that e-commerce via Bitcoin is ready or feasible for the masses. Nor do I think that this move would actually spur additional demand for bitcoin - I don't think that people will go buy bitcoin just to pay their taxes with.
Sure, it'll give Bitcoin additional "legitimacy" in our eyes, but to the public, the reporting is already neutral to positive, I would say... compared to a couple years back, no one is implying that people investing or speculating with Bitcoin are criminals. The thing holding people back from bitcoin isn't a question of what the government thinks, more it's the lack of places to spend it (yes, this is one new venue), uncertainty about the currency and how it works, and the lack of userfriendliness...
SO even if both states adopt bitcoin for tax payments, I don't think the demand will necessarily increase nor will the price get much upward pressure.
That's just my thought, though...
Sure you're right with all what you said.
But 2 states accepting it to pay taxes with it will reduce the negative image of Bitcoin in the publich as just being a criminal currency.