The pressure fields of the left and right part of a swept wing interfere at the center, causing a drop in lift. The Horten brothers called this "Mitteneffekt", and it was never properly translated into English, so the German term is used. The Hortens increased chord at the center trailing edge of the wing, reducing local sweep and increasing the area for lift creation. This helped to fill the "hole" at the center and at the same time allowed them to better enclose the pilot.
Lift distribution over unswept and swept wing (picture source)
The same is achieved with the reduced trailing edge sweep, airfoil change and change in incidence at the wing center of airliners. Since this part is occupied by slotted flaps, the rounded trailing edge contour of the Horten planforms is not possible there, so a straight line is the best solution.
Large wings need heavy spars, and saving some spar weight goes a long way in reducing lift requirement and, consequently, drag. While smaller airplanes do not profit much from an increased wing root thickness, larger ones can save hundreds of kilograms by increasing their root thickness. Since the flight Mach number must not suffer from this thicker root, the simplest solution is to extend the wing chord at the center. (Sorry, the link leads only to a library, but the thesis gives extensive proof.)
A nice side effect is the increased space for housing the landing gear.
Interference between fuselage and wing will cause separation there to start earlier than on the clean wing. Also, the superposition of the flow fields of fuselage and wing will cause shocks at a lower flight Mach number. Therefore, aerodynamic efficiency both at low and high speed is increased when the local lift coefficient drops near the wing root, so the flow has more margin before shocks or separation start. By increasing root chord over what is required for an elliptic lift distribution, the local lift coefficient can be lowered while the circulation distribution stays elliptic.
With an unchanged leading edge sweep, Mach tolerance is not much affected, but the lower trailing edge sweep is very helpful for increasing the effectiveness of the trailing edge flaps.
Regarding the word "Yehudi": This is the first name of a famous violinist, but I do not connect it with a wing planform.