Revisiting the topic after a bit of cooldown. It seems neither fish nor meat, or both. What are the facts, what the interpretations?
The widget blueprints use standard crafted components as well as common materials which is positive for their ailing markets, but then nanocubes on top. The end product is useless (and this is explicitly stated) except for recycling in the next higher level blueprint, the final one must be tt food then. The only purpose the blueprints exist is for their side effects. The ArMatrix weapon blueprints are composed in the same way, but their produce is definitely useful and desirable. Even looks very competitive at first sight.
That the widget blueprints use standard components and materials makes it unlikely they are intended to replace EP. The point was made that those actually increased crafting volume manifold because they use only tt ingredients and it was seen as useful to bind or isolate a certain clientele, the end of which is still hotly debated however.
Another point was made that if other filler materials were used, e.g. low-markup animal oils, it would rob MA of the freedom to nerf these. My spontaneous thought was on the oils that didn't go into the Galactica mission, so the strands would be separated and thus don't take away the possibility to implement directive measures on either side.
Since it is also stated in the component bp descriptions that they may still receive changes, could it be that it just wasn't finalized for this VU what other materials should go in, or they want to study how the new system plays out before deciding? Too many changes at once can make observation of their individual effects impossible.
There might be more plausible explanations for the use of tt filler material. There might be different explanations for why it is in the skilling blueprints and why in the weapon blueprints. I don't feel wiser yet.