Bitcoin is permissionless. Whether you, or Gavin, or Nick Szabo, thinks it should be used for a particular application is not relevant, if it in fact works for that application. Maybe your use of bitcoin as a value transfer protocol is burdening me by driving up the costs of storing objects for multiplayer games! Altcoins are often not suitable because there is not a well-maintained software implementation of the protocol for a particular alt, or because there is insufficient mining on that chain to foster adequate security. As it becomes more expensive to send tx on bitcoin, of course, there are opportunities for alts to fill certain niches. Just as there are opportunities for people to find ways like sidechains, or other hacks, to get more out of bitcoin itself.