In general, we're just not great at processing symbolic representations. We haven't evolved to do so (unlike spatial, visual, auditory, etc senses for matching representations) and have only manipulated symbols for a few hundred years. I mean true abstract symbols, not hieroglyphics or other old symbols that still mapped to language / were still quite visual.
I believe it could be more compelling to figure out how to re-represent things instead of just scaling up symbolic representations. That helps make it more powerful and accessible, for everyone.
A good example here that Bret mentions in his talk is Roman numerals -> Arabic numerals. Or even typing paragraphs of text to Arabic notation for equations (y = x^2 + 1 used to be PAGES of written text). People used to think only super educated elite mathematicians could grasp algebraic ideas. But after they were re-represented, we discovered almost all 8 year olds could grasp the ideas!