Felix,
You have a most interesting point of view!
The question is, do you want the brand "Port" in the highend market or for everyone.
We may differ on this, but I want it for anyone who would like to enjoy it. Whether that is a bottle of basic ruby or a Vintage Port matters not. Who am I to judge someone who really likes their $10 bottle of Port because it either tastes really good to them or because they can't afford a more expensive bottle, or they just don't know that there are bigger and better Ports out there? I am not sure I know why you would think that keeping Port only for the upmarket clientele would be a plus, since you are coming from a consumerism stance in other facets of your post.
If the demand for a product rises the quality almost always drops.
Is this the rule or the exception? If it is the rule, then I can think of lots of exceptions. I will stick to wine here:
* Whether the tens of thousands of cases produced each year by Joseph Phelps in a classy bottle with a name that projects the epitome of quality year in and year out, Insignia works and demand grows each new decade.
* Dom Perignon Champagne is produced in crazy quantities like a quarter of a million cases, but in nearly every vintage bottled it receives solid ratings, while demand continues to strengthen.
* One more off the top of my head, Chateau Latour produces an average of 20,000 cases with its Grand vin and above 10,000 cases with its white wine. These are just three of a zillion example that I can think of that don't fit the mold.
So I hope the demand for good Port stays as low as possibe. This way prices will be reasonable and the producer needs to make a real good product in order to sell it.
If you're trying to be provocative, you've succeeded.

As a consumer I want the best quality for the best price available. However as a pragmatist, I also realize that the grower and shipper (in cases where they are not the same being) deserve to make money on the fruits of their labor. Just think that if it rains during the harvest, there are people who do not get to work and Port companies become financially weakened; and another year goes by without the quantity of great grapes needed to make the best Port possible. Who wins?
To your point, if demand for the best quality Port remains low and therefore less great Port is sold, then not only will prices remain low but the quantities "made available" will be ratcheted
down. In theory I understand where you are going, but how is this a positive?
Take your job or your friend's job or my job. If demand for the high quality product of the company we are involved with is undervalued by the majority, how long is our job safe? But this is not about job security. When prices are held down by low demand, the cash flow of a typical entity is gravely affected. In the Port trade, this is one major reason that has led to so much consolidation.