I think it's entirely possible that youtube is still in a growth phase (or they are treating it as that phase), where they see the goal as convincing people it's a real platform to visit for content, and recurring content (such as a network channel, or Netflix now), and not just that place hosting videos that you get links to.

Once there's enough people that see it as a network of content that they can spend time on, they can then start encouraging and optimizing for specific, high-impact items instead of recurring content. Right now they are in the "let's pump out as many sitcoms as possible" phase, and hopefully they'll progress towards a "let's release a couple mini-series and made-for-TV movies" phase (allowing that they aren't generating the content in either case, just encouraging it's production and dissemination by offering cheap hosting and monetization).