There might be a small misunderstanding regarding the "dialog". Once you've selected an area you're shown the outlines & can still modify them, and the buttons (Accept (for further editing in Spectacle), Save, Save As, Copy, Export) are shown below those outlines.
This approach seems objectively superior to your suggestion.
Sounds borderline implausible. If anything, that's not a typical user user case by far.
Okay? Weird comment.
> If anything, that's not a typical user user case by far.
The scale may not be typical, but the pattern (many more screenshots copied to clipboard than saved as a file) is something I see across all kinds of users around me, be they technical or even very much non-technical.
Let's not turn the defaults into "The Homer", okay? Allowing the user to choose their preferred action in the same step as allowing them to change the outline doesn't make things unnecessarily confusing, doesn't add unnecessary clicks, or anything else.