Well, with later you aren't deciding not to install, you are deciding to install, just later instead of now.Of course!!!! if Apple is pushing to upload every day and after you say "later" it prompts you to type your password to upgrade... Is not that we are thrilled, is Apple pushing you to do it.
And not only that... Now I need to upgrade my OS to transfer songs to my iPhone via iTunes. I keep upgrading and my OS makes the computer/ iPhone slower.