It's unclear how many skillups each of these recipes will provide, but it looks like 1-500 BS will be doable with only Ghost Iron bars. I presume the idea is for these recipes to be used, not ignored, so they will likely be more efficient than leveling the profession in the standard manner.
Given the popularity this route will likely have, I'd expect it to expand to the other profs as well.
My initial reaction is one of contempt for this change. It'll make old-world mats meaningless, people leveling mining might as well vendor their Thorium ore if this change makes it across all profs. We'll also see a proliferation of people with professions that are presently costly to powerlevel, which could destabilize many markets.
I'm concerned this will both diminish the feeling of accomplishment for dinging a tough prof 600, and flood many markets with oversupply since people won't have to exert much in the way of effort to enter those markets. The new lightning forge weapons, we might see them selling at mats cost, if it costs so little gold/effort to switch out your Inscription for Blacksmithing.
I don't know what the rationale behind this is supposed to be, people will like it because it will get them to 600 faster, but it undermines years of tradition in favor of near-instant gratification. Who knows what the economic impact will be, this just strikes me as irresponsible.