One of the things you have to also understand about older aged whiskeys is the evaporation component to aging in barrels. A general rule of thumb is about 2% loss per year due to angel share. So a 18 year old has lost about 36% of the initial volume that it started out as. This along with housing something for 18+ years and also having to wait that long for a return on your initial investment, all costs a lot of money.I am not familiar with NAS Scotch. I guess I have fallen behind on reading whisky journalism.
I have said the following before, but have never seen it quite spelled out in any text, although no one has ever corrected me: I highly suspect that longer aged whiskies most often involve barrels selected as the better barrels. That is, it is not just six years of aging that distinguishes, say, a 12 year-old Highland Park from an 18 year-old Highland Park. Otherwise, there would be a whole lot more 18 year-old whisky around. Aging is not inexpensive, but I do not see anyway six more years in the barrel could account for the price or the quality difference between 12 and 18 year-old whisky.
I really do not know how this bears on NAS whisky. To me, Scotland, like Cognac, France, has really gotten control of a tight relationship between price and quality, in that for the most part one does not find really great whisky for cheap. I do not think the same is true to the same extent as to bourbon and rye. There are still big bargains out there, and age seems to have less to do with quality when it comes to bourbon and rye. My favorite rye these days is probably Peerless. Not inexpensive, that is for sure. But the usual bottling is only two years old, and the special bottlings are only three. If age is crucial, how can that possibly be?
Also you really can't compare aging and costs from scotchs to bourbons. The extreme hot and cold climate in Kentucky ages whiskey extremely different from the effects of the cooler climate of Scotland. The fact that scotch uses used barrels and bourbon has to use new barrels also effects on how the flavor impact on aging as well. But in general the hotter Kentucky climate causes a higher rate of evaporation vs the cooler climate of Scotland, which is why you there is more scotch aged in the high teens vs bourbon.
But to me age statements are the end all be all of what makes a good whiskey. Does longer aging do different things to the whiskey, yes it does. But it doesn't mean NAS/younger whiskeys are bad. Its just different.