Cost of goods
Randy, if you sell to the public even as a side business, why is the time less valuable? Granted, you would be making soap anyway, but there is no material difference in the soap and the value of your time if you make a batch as a side business or full time.
Think of it from a customer perspective - one day they buy soap from you for $x and the next day it costs $y - the difference? You suddenly decide that you will include all of the costs of time correctly as you want to go full time at it. There is no difference in the product itself, so many customers will go elsewhere.
Not to mention, if everyone who soaps as a hobby price only to cover costs, full timers will have to stop being full timers! "So what?" someone might ask. Well, many of the trailblazers ARE full timers. They make, they sell and we all benefit from their experiences. And then we cut the rug out from under them because we, for some inexplicable reason, want to under price our soaps. Then they can't soap full time and blaze less of a trail because of it.
Then all soap is priced as materials + a little bit of time because no one can soap full time. Someone comes along who has a much cheaper source than you for materials and suddenly you are struggling to justify your prices - then it's you who isn't even covering the cost of the market from the daily takings (let alone from the actual profits of the day!) and unless you can lower your costs, you can't even sell as a side deal.
Under pricing leads to no good thing - not for the businesses nor the customer. A downward spiral to the lowest cost does not engender development and innovation, rather cost cutting and a cheapening of the product.