Hears how I see it.
Even though you can get great smokes for less, "premium" usually is a reference to price. The price could be related to extensive aging, quality of leaf blends,limited production, high consumer demand. etc. Daviddoff, Ashton, opus X, and so on.
ISOMs could cost less then some premiums but the limited availability elevates thier value.
A good smoke, make that a great smoke, doesn't have to be a premium. I just put up a post of my top three cigars- Not one is concidered a premium.