Knowing what needs to be developed is important. For PD one of my crucial jobs was to prototype upcoming features, work flows, aesthetics and more. This gave us a clear understanding what needs to be developed.
Designing from an IA, to have an idea how users will use the platform.
This type of testing dropped our ideas and brainstorming to one single design where I could moved forward and iterate from.
Some ideas change over time and some I thought brand new. For these types I prototyped future ideas or changes in clickable prototype, one that users, test users, and us can play with it and see what needs to be chaged or sent to review.
After wire framing and testing all other types of aspects of design and UX, nothing hurts to test if things look "pretty" for the user haha
