I don't see it as an enhancement but rather a tradeoff. It's harder to focus on specific ideas when stoned but easier to build relations between ideas, both are equally important. I also find I easily diverge in depth on every concern of the problem at hand, which may or may not be useful depending on the time frame.
Being stoned is a state of mind halfway between dreaming where you subconsciously imagine everything and being awake where you consciously see everything. If you play music you already know this as being in "the zone". Over time you get a feel for this state of mind and can easily get back there without smoking.
I suspect people who feel anxious when high are those trying to control everything as if they were fully awake. The big paradigm shift comes when you learn to give up control of your own thoughts to your subconscious. Just like the musicians who try to control everything about how they play and end up thinking about what others might think instead of imagining the sounds they should be playing in the first place.
Weed can most definitely help with your work by changing your perspective over it and thus exposing new relations between ideas. But in doing so you will also get a new perspective on yourself. This in turn expose the mental barriers currently blocking your creativity and there lies the paradigm shift. Being creative is something we all do from birth but lose as we grow up depending on our life experiences. Being high is a ticket for introspection where you revisit what caused the barriers to exist in the first place, accept it and then move on to be freely creative.
You might also want to check out Effortless Mastery by Kenny Werner. He talks in depth about the psychology of our own mental barriers and how to overcome them.
If you think of weed as a magic thought enhancer, it's not. It's a magic introspection device and the results of that introspection is enhanced creativity.