I guess I'm mistaken on what people are saying. If it is the "it's another box" argument, it just seems odd that it didn't come up on PS4 or WiiU. Why doesn't the PS4 or the WiiU replace the cable box? Because they are not made by Time Warner/Cox/Comcast/etc. Same with XBox.
Honestly, I think there is so much unknown right now that rumors are flying, fanboys and hateboys are abound. I'm planning on waiting until E3 before really starting the complaining. But then, I'll probably be right with everyone on the high Microsoft hate.
I think it's more a question of intent. Sony's been pushing an 'entertainment console' concept for awhile, but for the most part, those efforts have been mutually beneficial for gaming and multimedia purposes. With the PS4, they were quick to highlight it as a powerful system for developers and gamers alike. Sure, it plays Blu-ray movies, and you can watch stuff on Netflix and YouTube, but that's not the driving force behind the console's existence.
Similarly, Nintendo has consistently emphasized that the Wii U is about finding ways for developers to create new experiences with the gamepad. While I have a rather low opinion of the system, and find a lot of their efforts are misdirected, it's still clear that they're interested in gaming, first and foremost.
As a lot of people have already touched on, it was the exact opposite with Microsoft. They focused on voice commands, sensors, gestures, watching TV, watching movies, listening to music, and gaming was just a tiny fragment of what they're aiming for, which is the exact opposite of what should happen when presenting a game console. In their own way, Microsoft's basically trying to pull a Wii, by trying to step away from their existing userbase and appeal to people who would have otherwise never bought a game console. They want to sell this thing to Mom, Dad, and Grandma, so they can break free of all those pesky, complicated devices, and drink deeply from the Microsoft cup of designer living - who needs a bunch of fickle, often angry gamers when you've got an untapped market of millions?
I don't think it's as simple as whining fanboys. People are seeing the Xbox One as a threat to video games, and for a variety of reasons, but distaste for this thing is one of the biggest rallying points I've seen among gamers in quite awhile.