That's such a cynic and may I say arrogant take on things and on the important work designers do. One could equally argue engineers refactor code just "to justify their continued existence for the purpose of job security". Or Product Managers rejig priority lists only "to justify their continued existence for the purpose of job security" etc etc etc
There's a difference between designing because they are designing to please a middle-manager that has directed them to "innovate" in that corporate sphere and design that is meant to be used and enjoyed by an end-user in comfort, i.e. human ergonomics.
A design language fad I hated from day one is MS's Metro design language which Apple also adopted in iOS 7, the format of which is that there must be as much glaring white space as possible, the user must be kept guessing which part of the screen is a button or switch and stab randomly at it until they find it, fonts must be spindly and thin, etc.
