I agree that the suggestions are great; I'm also generally happy to see a letter like this take a clear tone without being aggressive or overtly confrontational. Re: the prevalence JS/HTML projects, I think that may just be a matter of simple base popularity; the web is the most popular development platform, and JS is the most used language on github (githut.info has great stats on this). If the letter gains steam, I'm sure we could expect project maintainers from other ecosystems to get on board.
