You don't need it no, it's up to you if you want it or not. You get two standard replacements on AppleCare+ far cheaper than what your carrier offers. Really AppleCare+ is a one time cost per device for 2 or 3 years depending on the device and is overall better than what your carrier offers. Whenever I've had AppleCare+ I never had carrier insurance. Again, it's your choice, whether or not you feel like you need have multiple insurance policies on your phone.