109 wings were attached to the side of the fuselage, it was actually a design feature of the aircraft that the wings could be changed without having to lift the aircraft onto jacks, since the landing gear hardpoints were on the fuselage instead of on the wings.
The wing attachment bolts were very much strong enough to hold the wing on within the prescribed flight envelope and then some. But a connection like that is always going to be less strong than, say, a solid wing spar going through the entire wing. So naturally, the attachment points of the wings were the weakest link of the wings, in the position where the cantilever torque is the strongest...
I wouldn't be surprised if the most common failure mode of the wings in crashes was to simply snap relatively clean off the fuselage at the wing root. Of course, typically some bits of mangled metal would stick out of the damaged area.
On the topic of general "wing snapping" in the middle of the wing, I sort of agree and sort of don't. It's true that the breaks seem "clean", in a way. They seem to follow the wing ribs, but I find it sort of unlikely that the main wing spar itself would give away that easily. Sure, after being blasted by some HE shells I would expect parts of the wing to break off, especially if the main spar itself is hit, but otherwise yes - I do think the parts of the wing clip off a bit too easily.
However, I think the physical damage modeling is already much better than on IL-2 1946, for two reasons:
1. The break-offs can happen pretty much anywhere along the wing or fuselage structure, whereas in 1946 you are restricted to prescribed debris chunks coming off. For example, wings are generally divided in only two or rarely three parts (root, middle, and tip). Some planes like Hurricane can fly without the outermost wing tip, most of them however can't. The damage system in BOS allows for wings to be cut off in much smaller parts, so it's already much more dynamic system.
2. Planes don't necessarily explode on high speed crashes or collisions with objects. In 1946, the collision physics was typically that if you hit something, parts come off your airplane. And if you hit something with the fuselage, fuselage explodes. In BoS, complete disintegration and fireball does happen with high enough speed, but there's much higher probability for skidding along the ground in a cloud of debris and hoping that the aircraft stops before pilot is killed by some collision forces.
Finally, as always, it's an alpha version of the game so far. It's entirely likely that they'll improve the visual damage to the aircraft... I don't even know if the physical deformation damage system is in yet.