Thanks for sharing your suggestion! I believe there is an existing bug from others with the same concern about the preview for string objects.
Please let me know if what you are suggesting is a different one. We usually know the primitive string value, and can show that instead of character by character, which I think Firefox does. I've worked on console formatting changes, but haven't gotten around to this one just yet. These posts, and star-ing crbug issues helps, please stay tuned.