Distinctive hammers and other tools get brand recognition and free marketing out in the field, ostensibly increasing sales - that's why all the tool companies have their distinct colors and you can see the type of tool someone uses from a distance. Matching chargers/batteries incompatible with other brands perpetuate this even further.
Someone IS designing all this, they just aren't optimizing for what you wish they were.
If it's an interface and not an art object, then the design is secondary to the function of said interface.
Good hammer is a good hammer, not a "distinctive" hammer.