You will almost always have your phone on you, you will not carry your camera with you all the time. If you value 'any-moment' photos, get a half decent camera phone. The good news you don't need to get a brand new Nexus 4 to get a good camera. I use a Sony Experia Arc (android 2.3, so kinda old now) and it takes very good 8mp images, I make 5x7 prints from it.
Remember that megapixels is a fairly useless number for judging cameras (all of them, phone, point and shoot, or pro DSLR). Find a phone that takes good pictures (iPhone 4S, Galaxy S3, Xperia Arc, plenty of others). Don't worry about ti being latest and greatest.