The necessity for Design

Engineering contrives new technologies; design makes that accessible to average users.
Technological breakthroughs won’t mean anything if they can’t be leveraged to meet user needs. Design maps technology to user goals, rather than creating technology-centered products. Moreover, design also makes the product easy-to-use,reliable, convenient.
Another thing a designer brings to the table is being able to think of all use cases. In absence of that, the system may break at places- not because of any technical shortfall, but failure to account for an edge case. This is especially true if you’re have a feature which is fairly unique.

Combining Technology 
Integrating the latest techs can create the next best thing? Maybe. But how do you combine them without making it look like a complex, incoherent meld?
Design process starts with understanding user needs, and then finding the most appropriate way to address that need. Thus, in a well-designed product, converging technologies feels natural. Design confirms all features are functional, and not included only for the sake of adding it.

Products are about utility, no doubt. But no harm if it also delights the user, right? Good design can establish an emotional connection with the user. 
According to Don Norman, there are 3 levels of design:

Visceral — first feeling about a product.
Behavioral — the total experience of using a product
Reflective — how the product makes you feel

Beautiful things never harm anyone, do they? Especially when care has been taken to ensure that the “look” doesn’t come at the cost of any usability .

Business Value 
The key to increasing conversion rates is by enhancing a customer’s impression and satisfaction of your business.And design is all about providing the best consumer journey on your business service.

Trust is a crucial factor which determines if an user will return to a product. How to build that trust? By thinking from the user’s perspective, stressing on the smallest details. Who does that?Yes, you have guessed it right — designers.