The purpose of shoving error details into "copy to clipboard" is due to experience from providing user support: typically, people only send a screenshot of the truncated error message instead of copy and pasting the entire thing. Requiring error details to be copied to the clipboard nudges (forces) these users to copy and paste the entire error instead of sending a truncated error message. Developers are likely to have the console open anyways; errors are also printed there.
This also looks nicer than before.