Egyptian art can be recognized by just about anyone in the world. Typically at first glance you know it can from Egypt. It does not take any special skills or a historian’s degree to do this. It is just such an original form of art that they used for about 3000 years. While the fact that their art is recognizable what is not know is why did they stick with it for so long.
This is my theory. Much of their art stood to tell a story that their people world read for years to come. The paintings and hyroglifics of Egyptian art can sometimes hard for people to understand as is. So you can imagine how any variation is this form could become confusing to the person reading it. Perhaps they did try to vary from their techniques but people did not understand it and therefore it was destroyed.
A farfetched example to this would be they way movies and TV shows are filmed. Much like Egyptian art movies and TV shows stand to tell a story. In this industry we have a very set method for filming. The footage is shot from a view that gives the viewer the best possible angle of overlook. This is the way it has been done for years and it is what people understand best. If this process is changed it can make it confusing for the person to understand what they are watching. For example take a look at the movies Quarantine and Cloverfield; these movies are filmed entirely in first person view. Because this is something we are not used to this makes a little hard at times for people to understand what’s going on.
So perhaps for fear of people not understanding their work artist used the standard style for so long. This way people would be able to understand it for centuries. We also have to considering the average lifespan then was barely late into the teens. So imagine if you only had that long to learn everything you would ever learn in your entire life. This would probably make it hard for anyone to go off the beaten path of the Egyptian art style.