1. It’s the writing system evolving rather than the language. I think in the case of the Indic scripts this could be considered intentional as the scripts were designed to be practical in the first place.
2. Designers need to be active but defer to the native users. Just because designers can help bring all the details and quirks of handwriting into type doesn’t mean users want to abandon the limits of their typographic traditions, which might be practical if not so beautiful.