For all we know, 100% of the Mac mini out there do have the problem.
How do you know that?
I'm following this thread from the beginning, read all posts, and there are reports of people not having this problem. People without problems are not very likely to end up reading this thread and report about it.
Apple was collecting MacMini's with problems, why? Because they couldn't reproduce it with random units rolling out the factory. So there are good units out there.
And probably a large batch of bad ones, with various degrees of severity.
when it hits it seems to do so randomly. Just because someone's usage pattern has kept them from seeing the problem, or perhaps even kept the problem from exhibiting symptoms, doesn't mean their machine is in proper working condition.
It seems randomly because it is randomly. Nobody found a usage pattern yet, because there probably is none. I've had it happen with no applications running at all.
Which would be exactly the wrong thing to do if it were a widespread hardware issue. It makes zero sense to keep pumping up sales, especially for gifts, if it ends up that they have to recall and replace the entire Mac mini line.
They have done it before. Forgot the iPhone 4 Antennagate story?
http://gizmodo.com/5589336/apple-antennagate-and-why-its-time-to-move-on
Same story. First deafening silence. Then act as if its a minor problem. Put a bandaid on it.
quote from above article:
"Only 0.55 percent of all iPhone 4 users have called AppleCare about the antenna or reception. (This includes Genius Bar visits, apparently.) That's around 16,500 complaints, out of 3 million iPhones sold. "Historically for us, this is not a large number," Steve said." end quote. Yet ALL the iPhone4 had the same problem.
--> how many % of MacMini customers that have the problem, will actually get a replacement or a refund?
Probably not that many, you see in this thread many decide to keep it, and wait for a firmware fix.
Some of them might not have contacted support yet, thinking a fix will come soon.
Add to that, many less tech-savvy people think it's their older monitor or TV, or their cheap cable that's acting funny. The flicker is not very frequent, so they don't care and aren't aware it's a widespread issue.
So the more units sold, the bigger the profit margin, even if some units must be replaced or refunded. This costs less then the reputation damage done by a public anouncement that all Mac Mini's were shipped with known video issues.
I'm not saying Apple isn't looking into the problem, they certainly are, they want a fix just as bad as you do. But if the only possible fix turns out to be replacing all units because it's hardware related, they will handle it probably the same way they handled things before.
They really can't afford admitting another failure right now, after the Apple Maps fiasco. iTunes 11 is also getting tons of criticism according to this active forum. The timing to acknowledge anything is really bad now, amidst the christmas sales. Stopping sales of the macmini would be sort of admitting too. They are not "pumping sales" as you put it. Have you seen any mac mini on the "black friday" list? although it's very suitable, new and affordable to most people.
Don't forget this thread gives a distorted view on reality. You can't know the percentage of people having the issue. It merely gives you an indication that you're not alone at all. Don't forget how rumours spread. A small hint with great uncertainty, is a certainty a few days later on another forum.