Why Didn't Samsung Use On-Screen buttons on the Note 2?

I've owned the original Galaxy Note, and in the time I've used it for sketches and note taking, I've always found myself switching between finger and stylus when doing sketches and needing the menu to pop up. Thus my surprise when Samsung decided to stick with physical buttons on the Note 2.

I just think it would have been more natural if users can use the stylus all throughout their interaction with the device without having to switch to using their fingers if they needed to pop the options available or press back or home. Nothing detrimental, but it's just more intuitive that way and I was honestly expecting they'd use onscreen buttons already.