Controllers have long been the input standard of choice for console games. Although they perform adequately in most scenarios, there are certain game genres where a keyboard and mouse would provide better quality of life to the experience. Up to this point current generation consoles haven't natively supported mouse input, but Microsoft is looking to change that.
In response to a user comment on Twitter, Xbox head Phil Spencer posted the following:
Keyboards are currently supported by the Xbox One operating system, but without mouse drivers it isn't practical for applications outside of text input.
Judging by Spencer's post the update should be very soon, likely during Summer. The big question will be how it's supported among games. Titles like The Elder Scrolls Online, SMITE, and Neverwinter could benefit tremendously from mouse support. This could be the beginning of many more PC developers pushing their games to Microsoft's platform, as well as uncommon console genres such as RTS and MOBA finding their way onto the system.
With keyboard and mouse support, in addition to the upcoming Windows 10 UI update, the Xbox One is quickly becoming a great option for those who want a gaming PC, but don't want to spend more than a few hundred dollars. The console will be receiving VR support, streaming to PCs of nearly any hardware level, and will even have mod support for Fallout 4. Whether or not this strategy will pay off in the long run remains to be seen, but if nothing else more options is always a good thing for consumers.