Believe it or not, PRS does not have a signature guitar with every guitarist with whom they have a relationship -- Steven Wilson and John Wesley both have PRS guitars, but no sigs. I suspect they only make a sig if one can be created that is sufficiently different from any of their lineup to justify it. And if the artist is interested. I'm sure there have been many aborted attempts at coming up with a signature guitar, but because of the wishes of either one party or the other, never came to fruition.
I don't buy or not buy a guitar because it's a signature guitar. I buy it because it does or it doesn't have a set of features that I want or don't want. I did try to recreate Gilmour's strat, but that's because I grew up on his sound and consider it an ideal to which to strive. I also love Oldfield's music, but I don't even know what kind of guitars he plays. I have a ZM now -- no idea who he is. I have a Paul's Guitar -- he's okay, I guess.
I love Alex Lifeson and Neal Schon, but I don't have any of their guitars. I have no idea who most of these people are, but I'm not going to rule out a Wampler pedal because it has a country artist's name on it (don't particularly like country much).
I guess my point is, I really don't care if it has someone's name on it, and I'm not really sure why you do. I read the words, but they just seem to be backpedaling -- you brought up the 15 year old thing, that's why I assumed that you associated it with your own juvenile years. Similarly, you brought up not wanting the sig to be a sig, so when you say "you don't really mind", that just sounds like backpedaling. It's okay to have an opinion, just expect it to be challenged once in a while. Just a friendly argument. Do you think it being a sig raises the price? Because it doesn't. There are some artists that insist on having an entry level version of their guitar -- Grohl doesn't have a PRS sig, but if he did, I suspect he would insist on having an entry level version, considering his view of pawn shop guitars (good) and people like me who chase tone through gear but should concentrate on practicing more (bad). But there's some that don't care, and only want their name associated with a guitar that they feel comfortable having their name on, but then it becomes an economy of manufacturing. I don't think DGT is any more or less expensive because it has Grissom's name on it, I just don't think the guitar would have existed in the first place if it didn't.