I have 30 different animations to make, but they all use exactly the same sized spritesheets, in exactly the same layout. Making them manually is incredibly tedious, and if I make a mistake (which I've done), I have to do them over again. If I could do it in code, it would be a matter of incrementing a couple of variables for each one and calling the same function.
For me, it would be a huge time saver. Whether it would make a different to project size and performance (both very important) would also have to be taken into account.