I like the comment of linking it in concept to a Keurig machine. The idea of pouring 1 draft beer of a high quality and not worrying about that quality lowering while working through 2 growlers worth is appealing the way a Keurig is - quick, easy access.
I can see the value of being able to hold the beer longer, though I'm guessing you'd still need to find room in the fridge for the bag. It seems like a lot of money when really, I'd rather just drink more beer.
Yeah, why not just sell the bags if they are so great? Why not create a valve and pour the beer straight from the bag. Keep the bag in the fridge, and life is good. No need for a $250 minifridge. At least, that's my thought, until someone proves me wrong.
Hardware might be adding pressure, but that would be a downside, as some (most, I think) beers are already carbonated. Short of homebrews, that are designed to carbonate in the bottle...but in that case, yep, sure, this would be great.
I liked the contraption a friend made. Found an old chest freezer for about $50. Took the top off, added a 4-inch wooden riser between the body of the freezer and the top. Drilled out holes in said riser for taps, put the top back on and boom - giant size kegerator.
Beer can be kept for a long time. So long as it's kept in a consistent temperature, and out of the sun. UV light will break down the alpha acids, in the essential oils that the hops provide; and skunk the beer.
If a beer is pasteurized, it can still ferment if kept in a warm area.
I work at a brewery and I get out of code beer all the time. It'll be good for at least a year.
Some beers that are hop heavy do lose a bit over time. However, they are still drinkable.