Personally I really like w3w and their solution is certainly novel, I take your point about an open standard but equally these people have worked to create a novel and effective solution so why shouldn't they be able to profit from their labour?
We could apply the same argument to say UK Postcodes, despite the creation of the system having been funded out of public money (when the Royal Mail was state owned) they still want to charge people for access to the dataset? At least w3w have a nice API and is free for basic use, more than can be said for Royal Mail