Yahoo! has apparently come to the conclusion that since so few uses Boolean anyway, they may as well not support it. That is a mistake. Power-users like librarians, journalists and researchers use them, and they are exactly the kind of people that influences the public opinion in these matters.
J. Klinger. Proceedings of the 9th International Conference on Conceptual Structures (ICCS 2001), volume 2120 of Lecture Notes in Computer Science, page 101-114. Springer, (2001)