These characteristics don't necessarily mean you will be unable to build great products or a disruptive business. They don't mean your startup will fail. But they would almost certainly cause you to fail the character test.
Admittedly, being awkward and ugly does put your startup at a disadvantage because it will be a bit harder to recruit and a bit harder to close sales. But I am positive it is still possible to succeed if you are delivering real value. The product will speak for itself.
So aren't such character filters a bad business decision for YC? Aren't they passing on great startups by paying too much attention to things that ultimately don't impact success that much?