Whats wrong with the current form factor... other than its been around for a while? Would you dump your hot girlfriend just cause you've been with her for a while?
Larger screen is a bogus point to make especially since you say you'd be fine with keeping the current size if there was a new form factor. In other words, its not about the screen size, its just about seeing something new for NEW sake (not because it'd be better but because it'd just be new).
New materials, again its all for the sake of just being new. The current materials are fine. I dropped my iPhone 4 quite a few times and it survived each time just fine. The current look is also very attractive to boot, nothing wrong with it!
LTE 4G, you probably don't NEED it. I can't imagine why anyone would need super fast download speeds on a phone, especially if it would sacrifice the battery life. Unless you are tethering, I suppose, and using the phone as your main internet connection but at that rate just get a personal hotspot or DSL ors something.
Improved front facing camera could be useful, but really for video conferencing what it comes with is definitely good enough.
LED notifications and gesture pad are the two things left, and that's really grasping at straws. I mean, who wants a phone that can shoot 1080p video, take 8MP photos, act as your GPS, manage your calendars for you, etc. if you can't make superfluous gestures (read: unnecessary since you can control everything by touching any part of the screen already) on a 2 x 2 centimeter area designated for them!