It's easier solder straight to the board with a high likihood of a better more reliable result (assuming basic competence with soldering and a suitable iron). The fly leads (magnet wire) from the motor are simply extensions of the motor windings brought out for termination. Cuttimg and joining will require that the individual strands have the individual insulation mechanically removed prior to soldering and you then have the compound problem of providing for satisfactory electrical and mechanical performance over time.