Everything might look good in the camera app preview, but it's really noticeable when you go back and look at your old photos. You see a lot of things you wish were captured better. That's from just a year or two ago.

I'm sure there are people who say they don't care about their photos having room for improvement, and sometimes you want better and can't afford it, but that's not quite the same.

I went from iPhone 4 -> 7 -> 11 -> 13. I upgraded on a shorter cycle from 11 to 13 so I could pass down my 11 to my kids. In each instance, the image quality has improved tremendously.

Going from 4 to 7 was a massive jump in terms of resolution. Going from 7 to 11 was a boost in color and clarity, despite being nearly the same MP. Going from 11 to 13 was a huge improvement in night mode and shooting speeds. Also, these are non-PRO phones, as I cannot afford the PRO ones. I imagine the improvement in the PRO iPhone cameras are nicer.

Every iteration has been an improvement to me, and obviated the need for a DSLR in every day use.