Fmann
we have a huge difference in opinion. Sense I am not a classical wing chun man, I cannot argue for the classical wing chun centerline principal. But I can argue for what I was taught in Wing Chun Do. (Bruce Lee’s fighting style as interpreted by James DeMile.)
Traping is widely misunderstood. If your interpretation of traping is to check an opponent arms, then you are right, you will be in big trouble when going against a skilled opponent, (like a boxer) BUT if you see traping as an enmobilizing or grounding techniques that off-balance the opponent, so that they cannot strike you, while allowing you destroy them.
THEN WE ARE TALKING THE SAME IDEA OF TRAPPING!
Through the sense of touch and control of the spring energy, you can feel what the opponent is doing as soon as the opponent starts. Making it very simple to stop his movement before he actually begins moving.
Traping a boxer is not difficult. If you know how to do it. You must remember that traping in itself is not a endall,be all by itself. The centerline allows you to be able to touch the opponent with either hand, by using one hand offensively and the other one defensively at the same time ,will greatly reduced the opponent ability to counter your attacks. The third and most important element of traping is to control and take away space between yourself and the opponent, A constant forward pressure will easily, if applied correctly will overwhelm all but the very best fighters.
The hard part in traping is to engage. Before you can actually make contact is where you are in danger. After contact HAS been made it is not difficult to trap the opponent.
Now Im not talking just doing x-traps, but using an element traping in everything you do.
By shutting down the opponent’s angle of attack, as well as useing some basic movements, such as taun soa, pak sao, fook soa, or ,lop soa. When combined with the strike while you are closing, become extraordinary. (Even chung choy’s if done properly have some element of traping in them.)
Once you get into contact with the opponent, the trick is to feel and respond to what the opponent is doing. These basic principles are common in many martial art’s. Judo ,small circle jujitsu, and TAI CHI all have similar concepts. The trick is to apply them.
Here is a simple exercise to prove the point I am trying to make.
Stand in front of a training partner. Raise one hand (as if saying hello) have the secondary do the same, much like if you’re looking into a mirror (have him copy every movement you do.) Raise your hand up to above eye level and lower it to mid chest level. (You do not need to go fast ) you will find that there will always be a leg of time, between when you move and he responds.
Now touch your hand to the secondary hand. (Lightly) try moving, you will find it very easy to follow every movement not only up-and-down but from side aside as well.
Step 3 now touch (hard) you will find when you move he cannot stay with you. Because his energy will be over committed.
If you keep A light touch you can feel and move when the opponent moves .
Of course it is never that easy in real-life. But the theory is the same. And through practice and experimentation you will find traping to be very very effective.
But again that is just my opinion 
sincerely yours C.A.G.