There are also profession-names for jobs associated with men (e.g. Smith), but not for jobs associated with women. Why is this the case?
Historically, virtue names could be used for men. E. G. Withycombe, The Oxford Dictionary of English Christian Names, 3rd ed,, p. 115, says
Faith (f.) first used as a christian name after the Reformation. Lyford 1655 calls it 'a name commonly used'. In the 16th and 17th C it was given to boys as well as girls. ...
Hope on p. 155 implies that it was given to boys. If you have other examples, I can look them up.
I don't know that anyone has suggested an explanation of why English names could be used for one sex or both sexes, or why names could change categories.
As for profession names, R. H. Reaney and R. M. Wilson, English Surnames, 3rd ed., p. 33, derives Baxter from Old English b{ae}cestre, fem. of b{ae}cere 'baker', but note only 2 cases with a feminine given name. P. 63, they derive Brewster from Middle Eng. brewestere, 'a woman brewer', but "Three-quarters of the examples are names of men", and Broster from 'female embroiderer'. P. 147, Dyster. P. 273, Lavender (washer), has Ralf la Lavendere 1268! ("la" + feminine ending with a male given name: it could have been a woman with what we'd normally consider man's name, which was not uncommon -- Withycombe covers it in her introduction, pp. xxxiv - xxxvi.)
I would not put much stock in so many male examples. English surnames lost their literal meaning pretty early, 12th - 14th C. Women were mentioned a lot less in records than men, so people researching women's names have a hard time of it.
This hasn't always been true. Male Puritans had religiously inspired names, some of which tended in a positive ('virtue') direction (eg. 'Praise-God), some in a negative. The link below gives some interesting examples. http://www.slate.com/blogs/the_vault/2013/09/13/puritan_names_lists_of_bizarre_religious_nomenclature_used_by_puritans.html