The maximise thing is definitely something that you adapt to.
I hated it at first, and I must admit I still miss it sometimes. It's not just that it maximises the window (in Windows), it locks the borders of the window too... if you do the same thing in OS X (which takes more effort) you can move the window around and/or get it a few pixels out from the screen border, which is not as good for Usability. It's not worth losing sleep over, but it's mildly irritating IMO.
However as I'm on a 20" screen now, anything maximised (other than Photoshop which has its own equivalent) would look weird.
Personal focus and lack of distractions are valid points from a Usability point of view... I'd love to see something a bit like Exposé which made everything except your current window disappear (including the desktop background, dock etc) so that your single window is sat on a plain canvas. I'd easily pay for a shareware utility to do so.