Just because it's possible to screw up everything, including optical zoom, doesn't mean that cropping is the better approach. Remember, we're not talking about actual zoom (and even in the real camera world, variable focal length comes at the cost of image quality). We're talking about two separate cameras offering two different perspectives, but typically also different sensors. If the main camera has a significantly better sensor and high resolution, cropping can indeed be a good idea. I mean, if the "longer" camera has smaller sensor with lower resolution, it's in principle the same thing as cropping a bigger sensor with higher resolution. That's just physics. The benefit of using optics to magnify image is that you can utilize the whole sensor with all of its resolution. I.e. you can use its full potential. When cropping, you're just throwing part (perhaps most) of the sensor out of the window. And you're only doing it because you don't have the space for proper optics. Because you're building a phone, not a camera. You can't get around it. It's just an exercise in putting lipstick on a pig.