I apologize for the double post, but I've come to destroy.
Lack of flossing leads to gingivitis, fool. Those tiny pieces of in between teeth food and plaque irritate your gums to the point of oral death and could have been prevented with a piece of string. String.
Sure, it just starts with swollen gums. But then they get shiny. And then they get itchy. And then you may feel a slight pain when some sort of pressure is applied. Then the bleeding starts, and before you know it your gums have rotted away and all your teeth have come (not) clean out.
Then theres halitosis. Stank breath. How are you supposed to charm others with your wit if your wit comes out paired with the stench of a dead yak? Then you'll need all sorts of gums and mothwashes and other meticulous stuff.
Then there's dental caries. Cavities. Horror, pain, and suffering, all in one. The decaying of a tooth until it rots away into a black gunpowder. And then you'll need a root canal. This is where the Big Man rips out the root and nerve of a tooth to the very core and replaces it with some fake, rubber non organic disgusting substitute.
Sure, if you catch it early there are less painful treatments. But you're already not brushing your teeth, so you probably don't care too much about your oral hygene.
So floss.