Design .:. the soul of the bass guitar
Feel
I believe that the way an instrument feels is one of the most important factors in good instrument design. By controlling physical attributes such as neck width and shape, scale length, balance, weight, body shape, ergonomics and setup an instrument can be tailored to an individual for optimum performance. These attributes directly result in the way an instrument feels which affects how a player uses the instrument and ultimately the sound.
Sound
The use of different woods does undoubtedly affect the sound of the instrument, even an electric one! It is difficult to quantify this effect beyond general statements about tone. I believe that harder and denser woods allow more sustain, clarity and have a relatively even frequency response. Softer woods are less dense and absorb vibration producing "warmth". Medium density woods are somewhere in between. While electronics are a large part of how an instrument sounds, the acoustic properties of the wood and construction methods used are first and foremost in determining the tone of an instrument.
Quality
High quality materials and exacting woodwork do provide clean looks, but more importantly they improve sound transmission which creates a richer, more full bodied tone. In addition, these well made instruments are designed to hold up to the rigors of a professional musician and last a lifetime.