Why do typical DC motors use brush contacts rather than just the conductors of the wire itself? Wouldn't the wires be more efficient/low wattage dissipation in that region?
You're not looking at what a brush actually has to do. Brushes slide, need to maintain contact, wear, and arc. So you need spring loading, low friction, resistant to welding and corrosion, and need to be soft and replaceable so they wear instead of the expensive, difficult to replace commutator ring, but not too soft or they won't last.
I also have a feeling you are imagining a bristled brush with copper bristles. Motor brushes do not look like that, at least carbon brushes don't. They look like block of graphite with a coil spring. I've never seen what a precious metal brush looks like in person.
EDIT: Searching around, precious metal brushes are probably more what you might have in mind when you asked your question. Little strips of metal cutouts to make fingers (not bristles) where the strip itself acts as the spring.
Because the armature reverses polarity each time the brushes switch to the next commutator slot. If it did not switch it would not turn. In DC motors, we need a commutator or something for converting DC power into AC power. The commutator (mounded on armature) is a rotating part of the dc motor. If we connect electrical wires to the commutator it causes problem nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor. DC motors were the first form of motor widely used, as they could be powered from existing direct-current lighting power distribution systems. Since the commutator is a rotating part therefor connecting the electrical wires directly the electrical wires will also rotate along with the commutator which is not a feasible option.