There are many more factors in aerodynamic design than just wing loading-- span loading (the flip side of aspect ratio), airfoil, finess ratios, thrust loading, drag, in all its components and installed high lift devices. A number of fighters have greater wing loadings than the DC-10 and perform fine, for their designed mission. Yes, under G loads they lose speed, but FAR 25 design is for 2.5 positive G and all of them possess the power to overcome the resultant induced drag.
Yes, airliners have undergone proof levels G-loadings, usually they have been associated with a deep nose-low attitude and no amount of G prior to breaking the airplane would result in a stall and "falling out of the sky".