When I initially switched many years ago, like many ex-Windows users, two of the most frustrating differences were not being able to Cut, and not being able to full-screen maximise simply. I was told to stick with it, adapt, and I'd eventually appreciate Apple's design choices. I'm sorry but I still miss both features (the double-click titlebar to maximise the most - those little coloured buttons are so annoyingly small, and I still feel that a full-maximise would be so much more productive for me - I can instantly snap into the use of an application with no distractions on the screen). It's been many years, and I sometimes feel now that the designers at Apple Inc won't include these features out downright stubbornness - they don't want to admit that in the two small but important UI features, they were wrong and M$ were right. How could it really hurt to include them?
Having never even seen a mac until I was 18, I am definitely no Mac fanatic, and have pretty much used windows all my life. I switched a couple of years ago, and one of the first things that I really loved was the lack of maximize. With windows, you are expected to work in a maximize environment, and that is how programs are designed. This makes it terribly difficult to use 2 programs at once. For example, I often want to convert a tree diagram on the internet into an omnigraffle graph. On windows, I would be Alt-Tabbing all the time. On my mac, having the image on the side is natural, and makes things far easier.
Also, you realize that most documents are meant to be longer (height) than wide, and so maximize is useless, since the edges are really of no use at all. I will agree that there are times maximize could be useful, however, I still would not want Apple to adopt a maximize button because developers would start making apps assuming that people only want their application on the screen at any one time.