The brands shuffle their designs to stay ahead of IP laws. Gillette made the definitive shaving razor in 1901, the patent subsequently expired and anyone could make it, now they make new razors every few years to stay ahead of the curve.
With nappies, the correct answer is reusable nappies. It sounds gross, but when you’re a parent you quickly learn to deal with all kinds of shit.
You also get funky designs and stuff. The insides are interchangeable, the oustides are fashion.