History of Photography

The First Camera was important because it paved the  way to current cameras. It also allowed for accurate drawing practice.
The First Permanent Images (Daguerreotype, Emulsion Plates, Dry Plates) were important because inventors took ideas from these cameras and made more improved ones.
Camera For Everyone was important because poor people were able to discover photography and fall in love with it which made for a lot of great pictures.
The Horrors of War were important because it shaped the way photography is viewed. Also the pictures showed people how bad the world actually is and that it needs to change. Some people may have never seen the horrors if it was not for pictures.
The Wonder of Instant Images was important because pictures were instantly printed through a chemical process.
Advanced Image Control was important because it lets the photographer control the image.
Introducing Smart Cameras was important because it is compact and always read for use. 
The Digital Age was important because pictures are now higher quality. 

Though not everybody would agree, I want to argue that permanent images are the most significant step in the evolution of the camera.  

I have several reasons for arguing this point of view:  
My first reason is images were now able to come out right side up and they were permanent. Photos before this faded, but this sparked the new era of photography.

A further reason is that this led to a lot of progress with the development of cameras. New ideas formed which led to more experiments and better technology. 

Furthermore if it were not for this important step photography would be very difficult. Images can hold sentimental value and the threat of it fading could be horrible for some, but permanent images change the game.

Therefore, although some people might argue that instant images are the best I have shown that without them being permanent it would be hard for people to become attached knowing that they will fade. Some of the greatest pictures are very old, but because of the step I argued, they are still around to appreciate and learn from.