There are more markets that just hardcore gamers. When I look at PS4 there's nothing for the whole family. Only a gaming console with a "me too" TV and motion attitude. Even though X1 plays games it's not a gaming console targeted at hardcore gamers at all. Hardcore gamers will be satisfied with it of course but so will casuals and families. People that want applications that are better with Kinect will get satisfied, people that want TV integration will get satisfied, hell even communicating through Skype with Kinect is a selling point over PS4 (though MS might allow PS4 to do the same with Skype).
I'm not saying PS4 is bland compared to X1 but it looks more like a dedicated gaming device than X1. There is a market for dedicated gaming devices like there's a market for multi purpose devices like X1. Both will sell well to their respective market.
