For a founder who builds platforms, the most critical mission is to capture the imagination of creators and let them thrive.
Think of clothes and air. All platforms should look and feel like it is not there so they will not block creators' imagination. It explains why the final version of a phone is just a piece of metal with no lousy elements. If it is hard to imagine, compare a Nokia N gage with an iPhone.
Fashion, on the other hand, must be lousy because it IS the creation, it is the tone and the voice.
Thus, if you are building platforms, the perfect UX is either a chat-bot UI or a blank canvas. There is nothing there, but your mind.