This is truly a chicken and an egg question.
It is definitely a team afford between engineering and industrial design teams, I have lots of experience in designing consumer appliances, first step is to have very loose dimensional constrains determined by industrial designers in mind, that’s what engineers and technical team would use as a guideline to proof that technically the geometry can work, or not... and what must change in order for it to work.
Once a proof of concept and a working model are finalized, it’s time to make it pretty.
At this stage technical KPIs, aesthetics, ergonomics, packaging requirements, shipping constrains (how many boxes will fit into a shipping container) and more are all working as a team to come up with an amazing product.
Customers deciding – is a terrible idea! Customers often have literally fantasy desires which geometrically and functionally aren't possible... at least not on this planet LOL