Having read through what you've said, Roth and Minerva, I've changed my views on locking recipes. I'd like to see it go.

So far I've been lucky; I've been able to get friends to make things I can't and I've had something to offer them in return. I guess that rosy situation was part of what the devs had in mind.
However, I've only been able to craft 4* for a couple of weeks. When my friends are busy or there is nothing they want from me in return, I'm going to have use the MB and I've already noticed that the goods from the less popular specialisations are priced considerably higher than the goods that I can produce (since I chose three of the most popular ones).
Clearly, increased competition does drive prices down, so not locking recipes would benefit everyone. Omni-crafters could go back to being self sufficient and prices would be more favourable for buyers, both the single-crafters looking for materials and non-crafters looking for crafted goods.