The speakers of Proto-1 had a relatively egalitarian culture with small groups, relatively little specialization, and no writing, formal education, or complex media, so there weren't as many opportunities for different registers to develop as in a more modern language. And they were mostly concerned with places at relatively short distances from their homes - opportunities to talk about the world as a whole arouse mostly in the context of telling and retelling their myths and stories, and on those occasions, they used rather exalted registers (to the extent that they had them) anyway.
But I plan to shorten the term more and more in the descended languages (if I ever get around to working on the descended languages).