Tale of two condiments

Why has mustard in the United States improved so much, but ketchup has stayed largely the same? Why are some sectors more prone to innovation than others? What constrains innovation from the consumer side?

Here is Malcolm Gladwell’s excellent account from The New Yorker. Here is an archive of his writings for the magazine; he is also author of the best-selling The Tipping Point. Check out Gladwell’s work if you don’t already know it.