This was intentional to allow the error handling to be completely isolated into the HTML files that are not dependent on other code execution (including clientlibs). The impl for these HTMLs can be in isolation without any consideration for what other clientlibs are being included/not-being included.

My rationale is if you're throwing errors, then duplicate/inline CSS is the least of your worries.

the .cq-wcm-preview dependency is more of an example of how to "gracefully" handle edit/preview switching without reload.  

WDYT?