I don't quite understand this reasoning that because something becomes widely known and liked it somehow detracts from the coolness factor. Unless this popularity detracts from the quality of their work it doesn't really matter to me. I'd still buy a fed 52 deck even if it was very popular because the artwork is that good. I don't see how becoming mainstream inherently detracts from the cool factor of something.
It's more along the lines of something becoming bland and generic when it becomes mainstream. It takes away the thrill of the discovery of something new and truly original. If you walked into a unique restaurant serving well-prepared food - let's call it "the Airdrome" since it's near the local airport - you'd expect a unique, original dining experience. There was a real restaurant called "the Airdrome" in Monrovia, California in 1937. The owners, a couple of brothers from New Hampshire who got the place from their father, relocated the entire building in 1940, gave the place a new name, and it was all downhill from there.
Why, you ask?
Well, the new location's name was "McDonald's Bar-B-Q", which got shortened to "McDonald's" in 1948 when the brothers, Maurice and Richard Kroc, decided to streamline the menu to just six items, fire all the carhops and make the place a self-service restaurant with an assembly-line kitchen... I'd wager that if you stepped back in time to that original Airdrome restaurant in 1937, the food was a helluva lot tastier (and less carcinogenic) than the dreck that all modern McDonald's restaurants crank out by the megaton every day in 2014.
The thing of it is, naturally, that this restaurant chain makes container ships of cash, countless times more than the original place ever did, largely because it serves the masses rather than catering to the individual or a small group of people. Whenever you're dealing with something becoming popular, you're dealing with something that's about to be stripped of what made it unique and original, to be replaced by what makes it easy to create and easier to consume.
In terms of custom decks, you'll find a certain amount of homogeneity develop as the product goes mass-market. Everyone knows that USPC is making their own "custom deck designs" and that there's a handful of decks that take Kickstarter by storm and generate a lot of attention. But where would the little companies fit in this picture? People like Uusi, Encarded, Midnight Card Co., Big Blind Media, the former Circle City Card Co., etc. would end up like any other business that USPC has ever competed with - bought up and added to the collective, stripped of their uniqueness and commoditized for mass consumption. And yes, there's a HUGE amount of irony in that USPC is competing with its own Custom Department customers, to the point of even plagiarizing designs and selling them as their own creations (Coterie Bee, Bicycle Professional Skull & Bones).
It really has little to do with some hipster kid in a beard and a porkpie hat declaring them to be cool or no longer cool, and everything to do with preserving that which is unique and special in this world instead of having it stripped away and replaced with the bland, the generic, the tasteless and the mass-produced.