...that appearance matters?
Just ask any designer.
The truth is that the high-quality product, application, or site without an appealing design does not worth that much because in the modern market if you fail to attract attention immediately, you drown in the competition equally as fast.
And pleasant appearance is the most straightforward way of attracting positive attention. Moreover, visuals determine user experience.
The formula is simple. If people enjoy watching and using your product - your design is successful. That is why a good UX/UI designer is as important as a good developer.
Moreover, do not forget about the power of the first impression. If your service is amazing but its design is rather doubtful and not that appealing, your users will always subconsciously remember that first impression they got when opened your application or website for the first time. For sure you do have at least one service you often use but think that its design is intolerable and quite far from “intuitive”.
All in all, we enjoy observing beauty, interacting with it. The accuracy of symmetric lines, a harmony of colors, or even the magnetism of ordered chaos is difficult to resist. Staring at something appealing is definitely a pleasant way of procrastination meditation.
However, never forget to strive to perfect balance between great design and exceptional functionality.