Currently, a villager without a profession has a really huge radius in which he "sees" an unoccupied workstation. It looks really unnatural, when he takes a profession without the workstation even been seen nearby. I suggest that the radius in which the villager sees the workstation should be significantly reduced, or maybe he should at least have a direct vision of it to take a profession (that is doubtfull though, because in real villages it could take ages for villager to spot a station which is inside a house, you know, but it at least sounds reasonable).

Consider the attached screenshot. To the right we have a cactus-farm with a composter to produce bonemeal. To the right of a crop-farm we have a simple house, and there is a composter also. Right behind the Nether-portal we have a villager breeder, and if you have a close look there - you'll see a man in a straw hat, because he somehow "saw" the composter which is disgustingly far away from him. This looks really unnatural, especially taking into account that he is supposed to "work" at a chosen workstation - he will never ever have a chance to come even close to it