3 parties that should have design input: 1
3 parties that should have design input:
1. The designer (assures the design is usable, consistent, aesthetically pleasing, etc)
2. The product owner (assures the design meets user needs)
3. The developer (assures the design isn't needlessly complex to implement)
And needless to say, #3 is easy to overlook. Developers can, and should, have some input on design.
Needlessly complex design can lead to countless hours of wasted development time.