This is true. But there is some latitude here. Classical Karate generates power in the rear hand punch by pressing the rear heel into the ground, straightening the rear leg, torqueing the rear hip forward while maintaining a centered position, and throwing a punch directly from the shoulder with the fist horizontal and the elbow outward. Classical boxing generates power in the rear hand punch by throwing directly from the shoulder with the fist horizontal and the elbow outward, but raises the rear heel while rotating through the lead foot to send body weight forward and essentially torque the whole upper body. These are very different biomechanics when it comes to generating power. Throwing a punch with the elbow down and coupled to the hip with the COG in the lower abdomen or pelvis is a different biomechanics than throwing a punch with the elbow flared out and swinging from the shoulder with the COG in the middle of the chest.
In Wing Chun we train to do things in a certain way. Why abandon that under pressure? And if you (generic you, not you personally)find that you can't make what you are training work under pressure without altering it significantly, then you need to re-examine your training. Either you aren't training hard enough, you aren't training properly, or you need to change what you are training.
I try to go by the old adage...."fight the way you train and train the way you fight." Military combatives does this. Western boxing does this. Kickboxing does this. MMA does this. Why shouldn't Wing Chun?
Again this brings about the question,what is YOUR Wing Chun's purpose? You stated yourself, that you found TWC to be the most realistic branch when it comes to use. I think everyone will agree, TWC is significantly altered from Yip Man WC, which is itself altered from its roots. Seems to me Wing Chun is flexible enough to be altered to suit the need and still be considered Wing Chun. Some branches, such as my own, believe WC to be an art based around someone grabbing you, not punching you. That it is more of a close quarter stand up grappling/hitting method, and as such our mechanics & tactics reflect that. For my branch it is mostly a method of refinement for that range based on those tactics & not boxing, my branch is based on the clinch. So it isn't an effective long range boxing method.
TWC and WSLVT are based on boxing and its alterations reflect that, so they're not effective grappling methods. Branches that dwell on Chi Sau mastery reflect that and generally lack realistic ability all around. It becomes counter productive to use your WC in a manner not consistent with how its trained or developed thinking it will work simply because there is some crossover in range or tactics.
People always state that Wing Chun is a conceptual art, this isn't entirely true. Boxing & grappling are not bound by form, most branches of Wing Chun are. The 3 forms dictate how it should look, be positioned, move etc. People argue that the forms are just repositories of principle and theory, yet always reference the movements and patterns in them to justify their reasoning or stress their point. This isn't conception, its form. San sik methods, like boxing & grappling, are less strict in theory and less rigid in movement, they are more conceptual because there is no pattern that dictates exactly how it should look and move.
Precision and refinement come through actual use in real time. This is also true to an extent in WC, but WC also stresses "proper" movement through repetition of form. While similar, the major difference lies in a loose platform (boxing, grappling) vs. a predefined platform (Chi Sau) used in Wing Chun to develop this refinement. Being bound by parameters and rules that state if you violate them you are no longer doing Wing Chun, is not conceptual.
So this brings about the question, is your Wing Chun strictly conceptual? If so, the forms aren't necessary, so why cling to them? They'll hinder more than help. Conception isn't bound by form, form is bound by form. This isn't to say that a degree of conception can't be or isn't found in form, it simply states that alteration is limited to the parameters set by form. For those that want it both ways, you can't have your cake and eat it too. It's conception or form, there is no happy medium, pick one.