Some good points & info already shared in this thread. As other's have mentioned, this idea has been open for several years and we've gone through a few editor updates/versions in that time. I just wanted to post a comment that summarizes some of the issue right now:
Standard Ctrl + V copy/paste will paste the content with the formatting from the original source.
If you paste with Ctrl + Shift + V (Option + Cmd + Shift + V in Mac) the content will be pasted without formatting. When this happens the destination formatting applied should be whatever defaults are set on the Design tab in the editor.
The template defaults can be overridden at the block level. I imagine knowing to use Ctrl + Shift + V will solve the issue for some. For others, I'm guessing "destination formatting" is considered the formatting at the block level and not the template default, which also makes sense. Feel free to clarify to make sure we're capturing the feedback more accurately. The ability to paste without formatting was feedback that was considered and planned for with this current editor, but it seems like the thought was to apply the global styles.