Chickens and eggs. No miners = no traction.

Especially around here, where every time a coin comes out that does not involve mining its announce thread starts accumulating complaints and scam-accusations!
Admittedly exchanges also give traction, but there are advantages to not being on exchanges, because regulators are more likely to question a game-currency's status as being "just a token used in games" if exchanges for it officially exist. (Notice that until quite recently most/all large MMORPGs forbade buying/selling game stuff for real money? Until a year or few ago some big name one put a real money market right into its game, likely after racking up oodles of expensive legal fees...)
Player groups such as guilds, parties, associations and such like GRouPcoin not just because it has GRouP in the name but also because it does not "officially" have exchanges to/from "real money"...
CoiLedCoin thus far has that same "niche advantage".
Hunter coin's merged mining in SHA256 never worked for me so I gave up trying to include it in my merge.
-MarkM-