Design is much more than just making things look good. Design is a method of problem solving, helping to make the complex more clear and easier to understand. Go beyond purely user-centred as design needs to be fully context aware. Design aligns business viability and technical feasibility with the needs of the customer.

Better understand and empathize with your users
Identify problems and pain points to solve
Visualize complex information
Propose potential solutions quickly
Encourages you to try and fail early (and cheaply)
Iterate > Prototype > Test loop
Mold relevant, holistic and balanced concepts
Saves technology development time and money
Visualizes your solution in increasing detail
Builds and communicates a clear and concise vision
Create compelling presentations
And eventually, good Design will make everything look great