Amazon.com: Have there been any big wrong turns in computing in the last 25 years? Do you regret any of the directions that it has taken as a lost opportunity?

Knuth: The thing that I regret most is that people are trying to patent algorithms. This means that it is becoming impossible to write software unless you're a big company. This climate is going to stifle progress. If such attitudes had existed back then, I would never have been able to write this book.

Which is ironic, since Amazon is one of the original companies to use software patents as a weapon.