I'm not indigenous but...
I don't necessarily agree that anyone can't give it a go. Most other traditional art styles, especially western ones, are open for anyone to try. You'd never hear the argument in this day and age that a sherpa shouldn't be allowed to walk into an art class and paint a bowl of fruit, or that a native american isn't allowed to play a harpsichord.
Art styles evolve over time, as has indigenous art, and should become increasingly accessible to the general population - to those who can create it and/or those who can appreciate it.
The symbolism of indigenous and pacific art styles not only comes from the elements themselves but how they are arranged. I feel that the symbolism in the arrangement is more a case of how the creator wants to use the elements and tell a story (or not tell a story) rather than following traditional set rules.
Having said that, it can be a hard art style to master. I've done a bit of work in the past and find it best to do bit of research and work out symbols and techniques before making anything. Same goes for Maori and other pacific art styles.
