I think the way it works is:- you pay your money and get a very large amount of perfume (with creed it is ten litres) initially. If you want more, you order more later (presumably at a lower cost as no development this time). The formula remains secret and only orderable by you until you die after which the house is free to market it if it so chooses.
I think much of turin's point rests on the quantity issue. Ten litres is a silly quantity of perfume for one person, yet it is financially silly to make less. In fact, it makes financial sense to make more. The actual cost of producing more, once you are producing some, is minimal. The price you pay is largely: 1) for the perfumers time and experience (fair enough in my book) 2) the exclusivity (ridiculous in mine and Turin's books) 3) a relatively small cost for the materials and packaging.
I also agree that most people are in no way qualified to make the decisions necessary. I am more aware than most people (non basenoters) about notes, construction, development etc but know I do not know enough to develop my own fragrance. I know some people here do make their own concoctions, they may know more, but I suspect many of them are working on learning that which a highly trained and experienced nose knows.
I can understand if you know a lot about what you want and have the money to burn (e.g. someone here may be looking for an ultimate rose accord for them and have a good idea they want it minty and fresh) but these must surely be very few.
(After the revolution, bespoke perfume services will only be available to those with at least two years basnotes membership, over 2000 posts, and proof from their bank that they have put their livliehood at risk by overspending on the failed search for that which they would like created