It's not just the filesize, it's also the rendering speed. I'm not saying SVG is terrible, I'm just pointing out there's probably room for a smaller vector format that's more focused on the needs of modern websites.
Your criticisms are based upon nothing.
The rudiments of the vector description is extremely concise. That it is XML is superficially irrelevant, and if you really think the text markers are so important, consider it a highly compressible binary format via GZIP. Ultimately it doesn't matter.
I've never seen any metric that holds SWF as being more efficient than real-world SVG.