design
In production development, along the years, most design stages could be avoided. They are just maquillage, basically unnecessary.
Unnecessary changes, when adopted to a certain degre determine or shape aesthetic fashion trends. Needed changes, instead, refer to industry practice trends and, at a higher knowledge scale – when they’re considered revolutionary – paradigms.
To be effective, changes – necessary or not – must be adopted. Forcing them (for example by law), without a spontaneous and relevant degree of adoption, won’t assure their survival if the imposition ends.
The most effective and long-lasting trends (either aesthetic or substantial) are adopted unconsciously by a majority of adopters, by imitation of cultural leaders aka agitators (independent) or evangelists (client-biased) or mass replication for acceptance purpose.
The constant profit race feeding the unfair accumulation process determined and welcomed by capitalism (a political ideology like all economic models) is the primary driver of design changes – not necessarily an evolution -,particularly superficial ones aka styles.
Design stages are the proof of planned obsolescence – either technical or aesthetic – often supported by laws that in theory have the opposite aim.
Profit is a bad prophet.