Why does this not exist;? Something so damned simple!
You don't really need to link these clauses together, it sounds clunky. A question should probably be independent the vast majority of the time, and when it isn't it should come last.
Like this: Something so damned simple; why does it not exist? I think it sounds way better and is easier to read. If you need to describe the tone, that could be a sentence that comes before or after. It's easier to do this in dialogue than in thoughts, but still doable either way.
I think what you're proposing is unnecessary when you could just rewrite it to flow better. I can guarantee you that there's probably a better way to structure your sentence than simply inserting a new form of punctuation.