You are not forced to update, you know... It doesn't update automatically and without asking, like I've seen Windows do. But it's nice to be able to update often, especially since there are some nice features and/or bug fixes in every release.
However, if you don't want to download the whole thing, you might try to get just that one feature - and it will most probably work!
To update or not to update - you are free to choose in all aspects of it, that's what I like.