When we first started the show we were doing way dumber more youtube-y content (largely due to the interests of the producers, not PBS — look up the Majora's mask or farting in space episode). We got a ton of initial feedback early on that people wanted more actual science stuff, and it seemed like there was effectively no upper bound for what people would "tolerate" in terms of actual science vs. IFLS-core content. I think people honestly just like the challenge of understanding the show.