The functionalist argument has an elegant simplicity: a chair that cannot be sat on is not a chair. Purpose precedes appearance. But this framing sets up a false hierarchy. A chair that is functional but deeply ugly will be avoided. A chair that is beautiful but slightly uncomfortable will be used every day. Function without form is a prototype; form without function is sculpture.
The most sophisticated products treat form as a communicator of function. The shape of a well-designed door handle tells you whether to push or pull. The weight distribution of a good pen tells your hand how to grip it. Dieter Rams called this "honest design" — products that do not pretend to be more than they are, but whose form makes their function immediately apparent.
In software, the false binary becomes: features versus aesthetics. Teams that default to raw functionality ship products that work but feel like work. Teams that default to aesthetics ship products that feel beautiful but leave users disoriented. The discipline is holding both simultaneously.