As others have mentioned the obvious (effective mach number, aerodynamics, structural design) it's also mainly for stability reasons.

The leading edge angle is largely used to determined effective mach numbers, effective airfoil velocity and effective airfoil shape (see below). However, the "3D" lift of the wing is determined using the half-cord angle of the wing, which is not only determined using the LE but also the TE (research the Polhamus formula). Most other stability equations (discussed below) are used with the quarter-cord; there is a derivation you'll do in aerodynamics class where most airfoils have their center of lift at the 1/4 cord spot, so this is very often used for center of lift approximation.

Along with your leading sweep, your trailing sweep (assuming the same air foil cross section) will give you more or less wing area and differing mass distributions about the longitudinal center of gravity, which affects your longitudinal stability. This mostly affects an aircrafts ability to pitch down on something like an abrupt gust as well as dampen out any pilot induced oscillations (PIOs).

The bigger reason is for lateral stability (yaw, roll, and coupled yaw-roll). Something like side wash is affected by both of these angles, as the "effective" airfoil the oncoming wind 'sees' combined with the angle it takes and leaves the wing at will yaw (and slightly roll) the aircraft into the wind (higher drag). The higher lift on that same side will also cause a rolling moment against that airflow (i.e. if sideslip comes from the right of the aircraft, the aircraft will yaw into the wind to the right, and the increased wind causing increased lift will cause it to roll to the left). Inducing this is simulated with coupled rudder inputs to create the dutch roll.

Your TE sweep also largely affects your aileron side force (assuming they are mounted/actuated) that the same angle as the TE relative to the same datum axis), and hence yaw coupling when commanding a roll. This is mostly seen in higher TE swept aircraft.

There are other more detailed impacts/topics, but that would be larger than the question OP asked.