I was viewing some beautiful Caddoan artwork yesterday, and picked out some visual motifs that seem to repeat themselves. Before long, I had visited Wikipedia's page on the Caddo language, and I quickly scrawled out a proof of concept for a Caddo alphabet.
Why should Caddo languages have their own alphabet? Why not just use Latin?
Because your alphabet says something about your culture. If your language has sounds that Latin does not approximate, then custom letters are needed. (For example, English could use a letter like Thorn!)
A writing system crafted to complement your culture can be an artistic outlet.
More importantly, though: if your culture is distinct from American culture, and it has a language worth preserving as a vehicle for that culture, then a home-built writing system is one of many ways to promote that culture.
Here's my proof-of-concept Caddoan. The shapes were taken from Jeri Redcorn's sublime pottery designs, as well as historical photographs of Caddo art. I also admit a passing influence from Baybayin, since a few of its letter shapes are universal and beautiful, and correspond to some of the Caddo shapes I use. I adapted three.