It may be that I don't understand Mozilla, but I believe they should focus on Firefox, Thunderbird and MDN. Even Rust is sort of a weird CS project that you don't technically need, but fair enough, if makes Firefox development easier, go for it.
Mozilla get most of their money from search engine companies, so may they should start focusing on trimming down to the point where they could survive without that big Google check and drop some of the side projects.
And why is it that there's no "Support Us By Donating" button on www.mozilla.org? I feel there should be.