I disagree. The usage of features in Word undoubtably follow the power law, so there is undoubtably somebody somewhere who does use any particular feature, but the vast majority of people don't use them.
Pages doesn't have all of the functions and if you can't live without a particular function, it is obviously not a good replacement. However, for the vast majority of users, it has all the functionality that they will ever need and then some, without worrying about getting lost in menus of functionality that they will never care about.
I don't think Word is a best example for that. I'd say the wast wast majority of Word users use very basic features. I've seen my share of documents where spacing and centering was done using spaces…
Pages doesn't have all of the functions and if you can't live without a particular function, it is obviously not a good replacement. However, for the vast majority of users, it has all the functionality that they will ever need and then some, without worrying about getting lost in menus of functionality that they will never care about.