We're not comfortable making a tradeoff in which we sacrifice compatibility for the sake of supporting a standard. When we can do both, we do. When we can't, it's a much harder choice. Most often, we decide to be compatible first. The intranet is a different place.
Companies generally have standards of their own.
They choose a browser vendor, choose a form factor, and have control over what people do. They are using the technology of the Internet to create new information systems that are easier to use and administer. These companies request features from us all the time. They demand innovation. They want the features needed to create world-class applications, using the browser as the new rich client for those applications.