The reason I expanded was to explain the whole to understand the parts....
By your rational the Vt system is everything you want it to be and MORE
Thats when we get the confusion , we dont understand the root so we look for answers in the leaves...thinking this leaf is for this and this is for that and if they do this we use the low bong , applications and arm chasing ensues. We stand in front of each other doing so much chi-sao we lose sight of the fight.... to address your *
*You only pivot as much as you need to, this may mean pivoting for power, reach, angle or to resist force (this is more of an ecentric movement).
I only pivot to face you to attack you
*You can go to the inside or the outside, I normally go to the outside as you are more protected but being smaller once their hands are up it is more difficult to hit the persons head unless you go underneath. My teachers teacher always said it is better to go through the centre but is alot harder and you need to be better.
The system is designed to allow us to deliver flanking attacks , by design , we can fight from a perimeter in side stances , protractor , we can do anything ...% of constant fighting , read 'constant' armed or not will be in YOUR favor by adopting this thinking.
If you play chi-sao with a complying game player you can do whatever you want its only a drill. you can do it blindfold too standing on one leg while humming a tune
*There are a hundred ways of looking at the same move in the forms. Each move can be broken down to praticing a single technique (ie tan sao), you can think of it as a combined move of all patrs or with any variation you can think of (ie tan can be thought of as a strike or just a block) or can be thought of as a concept of how you move to different stimulis. I was saying one exampple of what the low bongs could be used for. I meant the bong is kept low and you step forward and do what ever you want with the other hand, I didnt mean two bongs. This is not to say that the other examples you have given are not valid.
You said it was the 'main' reason for low bongs , it isnt.
You have to have the whole of the systems thinking to make sense of the basic parts , ergo my digression into a knife scenario....everything is geared to allow us to maintain an attacking action, while maintaining the % factor, even if the arm is x'ed over while we turn and re-flank, shift to entry on us and flank, chase along a converging position , to a position we cans trike from while attacking , side shifting , facing in a flanking position....iow I have entered your flank , like I started on the dummy side...here I am and your moving backwards while I have managed to gain entry to your weak-side....you attempt to x over my arm, I have a lead leg and I am attacking with constant forward steps/pressure to maintain my striking zone . I use bong to knock your arm out of the way while still attacking . The height of my bong is only relative to your arm and mine at that point in time , the idea of bong is still the same , not an application of a grabbed wrist....or I can only do low bongs if I'm going forwards...sounds silly doesnt it...so if I have to do a higher bong like we do in chi-sao, it has to have the same ballistic removal force 'couple' with forward force I am also delivering ...2 forces one action 3 things at once if you include the step which delivers the leg force = to the amount of energy you push into the ground...but I digress even further ...
so if Im going forwards, hitting , and want to keep hitting with force , I make by bong move your potential force sideways, relative to my tactical flanking goal, dissipating your line of force by my ear/shoulder... as I deliver a simultaneous linear strike along the centerline, transferring the bongs clearing action to the vu that strikes using a 'tan' trained forearm angle, not to block but to strike .recovering the bong back to vu , using the tut sao actions to maintain an attacking rear free hand ...if you grab my hand I have bil gee , developed for just this grabbing idea....not chum kil. By design BG allows me to regain the relentless attack of the SLT/CK bubble without stopping the attack. Lop sao , bowing down elbows etc...all help us to regain the momentum of the attack without resorting to....."application z for move 45, facing , with one lg on ground."
You can have a 100 ways if you dont know the way to the destination. You can take the scenic route many do because they have no map. They ask directions from guys who are also lost but have videos for sale making them beyond reproach and a book series further compounding their ideas, doesnt mean THEY dont work , just not working for a single common idea of vt attack as defense, attack as defense , attack as defense.
*Some times you just have to block. This is never the prefered option as attack is always best but sometimes you are put in a position when you really need to block it and then attack. Especially when the person is better and bigger you need to keep in a good position to be able to strike him when the chance arrives, be this blocking, range or attacking him there are many options but blocking is always one of them.
How do you know they are better ? If you apply the thinking of the system, force has no place to rest on you , except when it grabs you , ergo bil gee.
The ideas of chi-sao arent to place force at the wrists and seek a place to put that force ...we dont seek out the arms to become functional in chi-sao , we simply offer random lines of force to each other with entry combined to develop instinctive angling away from facing force with force, we dot keep 2 arms extended either always man/vu, unless bil gee...we use 2 in fast rotation against one with overwhelming force to attack a weaker side with the combat idea to end the fight asap , not have 10 rounds or 5 rounds to play for time , wear the guy out , feel him out , back off and try again ...you CAN but its not what we are developing ...other systems have a combat variety of thinking that changes its delivery , thai boxing for one can become elbows , knees and straight shots with constant forward entry ...think about the idea of attacking as the defense...how would you develop to be able to sustain that idea ...
what techniques would you use to do it, straight lines, unthinking delivery to overwhelm the thought process of the recipient....% ideas rather than rigid rules . training drills specific to the delivery of the primary goal...willing partners developing each other for this goal. Drills that include methods to recover the ability to maintain the primary idea....a dummy to focus the arm angles on repeatedly with solid arms to develop ballistic displacement and a facing positions. symmetry of techniques so you could flow like water either side of the counter flow , seamlessly without thinking .
A relentless attack ....
I used to think like you, a lot of you , I would question what this was for and that. You wont find the answers in chi-sao, its simply a tool to build a greater idea.
I would think that we attacked center too because we do so much chi-sao like that, we get lost in the thought process. Out of this thinking Kwan sao is born, with turning force etc... the idea makes you think to stand there in the first place , like yu said they might be better , so why stand there and give them the chance to show you or take you down ...you fight like you train, many policemen got shot because they practiced on lanes , standing facing against a paper target firing back only no bullets ...over and over ... then someone fires for real and you stand and fire back like the range.