This move might take the pressure off of Mishra's Workshop, but it doesn't give much of an explanation as to why they are pumping colored artifacts and not simply enchantments:
Article: Colored Artifacts are the Future (Hipsters of the Coast w/ Mark Rosewater)
This makes perfect sense for color pie reasons.
From the discussion at the end, I don't think enchantments are being de-prioritized in any way, I read the shift as being within the artifact space. For example, if 18% of good cards are artifacts and they're 17% colorless 1% colored in the future it will be 1-17 instead of 17-1. I don't read the article as saying anything about artifacts being boosted ahead of enchantments.
I think there's a bit of a natural flavor differentiation between artifacts and enchantments, which Wizards should try to push further. Namely, artifacts sometimes tap and/or sacrifice to function, while enchantments very rarely do. Enchantments frequently have static abilities, while artifacts have these abilities somewhat less frequently. If I were in charge of design for Magic I would try to have firmer rules about what mechanics go onto what card type, extending the historical mix into something players can recognize intuitively.
so in an attempt to not produce further Smuggler's Copter/Heart of Kiran/etc they are incidentally make less cards that can be cast entirely off workshops.