Chris, you won't find many people on an NGC Forum who will tell you they pay a premium for a modern coin with a guy's signature on the label. Now, if you could buy a Saint Double Eagle with a COA signed by Augustus Saint-Gaudens, that would be another thing.
The guys are right....it's 99.9% marketing. You can debate having a modern coin graded and slabbed but at least you get something tangible with each: an actual grade (70 or 69 or maybe 68) and a nice holder that makes handling the coin easy. "First Strike" and "1st Day Of Issuance" and signatures by engravers, Treasurers, Mint officials, etc. are really not worth much at all, if anything.
That said, I do LIKE the modern NGC holders alot and when I do buy a graded and holdered modern coin, sometimes I will try and buy it in a modern NGC label. How much more am I paying for that ? Maybe $5, tops. If I buy another 2009 UHR Saint recreation I want one with the NGC label that has the side portrait of ASG rather than just the plain gold foils or other artwork.
But again...that's MY preference and I won't and don't have to pay much for that little perk. Some folks charge an extra 20% or 50% or more for 1st Strike, etc.