Milton Glaser has some fascinating thoughts:
I think this idea first occurred to me when I was looking at a marvelous etching of a bull by Picasso. It was an illustration for a story by Balzac called The Hidden Masterpiece. I am sure that you all know it. It is a bull that is expressed in 12 different styles going from very naturalistic version of a bull to an absolutely reductive single line abstraction and everything else along the way.
What is clear just from looking at this single print is that style is irrelevant. In every one of these cases, from extreme abstraction to acute naturalism they are extraordinary regardless of the style. It’s absurd to be loyal to a style. It does not deserve your loyalty. I must say that for old design professionals it is a problem because the field is driven by economic consideration more than anything else.
Style change is usually linked to economic factors, as all of you know who have read Marx. Also fatigue occurs when people see too much of the same thing too often. So every ten years or so there is a stylistic shift and things are made to look different.
I also find truth in what Milton Glaser said about lying:
Lies erode your ability to act. Ultimately the lie is an instrument of power.