Maxime; as I have not had even my first cup of coffee yet, I am going to disagree or question a few of your comments. Perhaps after the coffee's ready I'll see things more clearly
First, who are most bass players? To state that most bass players could afford an Essence in 1996, but that most cannot now, just doesn't seem reasonable. I would imagine that in 1996 there were quite a large number of bass players, especially those in their early to mid twenties, who could not afford an Essence. I would guess that most bass players in 1996 were buying basses that cost less than $1,000. These would be the Fender, Ibanez, Yamaha, Peavey, etc. that make up most of the stock of music stores and mail order catalogues. I'm thinking many of these players were working low paying jobs and had very little disposable income. And I'm thinking they were looking to pay less than maybe $700 for a bass. On the other hand, I would think that Alembic and other high end builders are selling more basses at the current Essence price or higher now than they were in 1996 at the 1996 Essence prices. With the ageing of the baby boomers, there are more older folks who've been saving their money over a longer lifespan, and who are inclined to buy high end electric basses, now than there were in 1996.
Second, I don't think it reasonable, given my above statements about the economic resources of most younger players, to expect the same quality of instrument if Alembic sold a bass that the majority of players could afford. Most players are buying basses that cost less than $1,000. It would seem to me that one reason Alembics are of such high quality is that they are built in a small shop of very talented artisans. If they sold a high quality bass for less than a $1,000, the waiting time for a new bass would be decades. To accommodate the demand for $1,000 Alembics, the company would have to hire more workers, which would mean a decrease in the quality of the work.
Third; I don't agree that no one should go through life playing anything but an Alembic. There are a number of builders that make very nice instruments. Not only are there lots of quality high end builders such as Fodera and Sadowsky, but there are good quality lower priced production line basses as well. For example, I don't think that you should be saddened to see someone playing a Warwick.
Finally, there are quite a lot of bass players who play bass just for the pleasure of being on stage. They don't care to sit at home and practice. They are proficient enough to handle the relatively easy lines that are required for the set list their band plays. They are perfectly happy with a Fender and the free beer the bar provides.
Well the coffee should be ready by now.