Set stances are perfect for one-on-one play sparring.
But in reality combat, one doesn't have the time nor opportunity to go into a stance. And if one does, he's wasting his time by not attacking or fleeing. Bruce Lee taught this by throwing stuff at people and noting that they would simply catch the object without thinking about it or going into a predetermined stance.
JKD actually advocates the use of the By-jong stance, a hold over from the Jun Fan days. Bruce thought that footwork was more important than stability for people his size and/or speed.
People my size, 5'11" and 215 would not be pigeonholed in JKD to the By-jong stance, though. Bruce's footwork was like tap dancing to my waltzing. Bruce was like a fencer in his personal style, but he didn't want anyone copying his style. He wanted them to use the science he laid out to develop whatever worked for the user. The Unifying principle to my footwork is the transition step, a method of remaining poised and grounded while moving. This fits my personal style of hit grab and throw much better than Lee's tap dancing.
A stance is actualy taken whether one knows it or not. It may have no name, but the position a technique is executed from is a stance. If one tries to remain moving while delivering a technique, it will have no power.
Bruce would deliver a punch before he stopped moving, but the punch itself was recieved when his lead foot came down. He theorized that his opponent would be forced to absorb more of the kinetic energy that way.
BSL was created in an era before modern day sparring competitions were held. That's why it doesn't have the standard moves we are used to seeing in point sparring competitions and movies. Because of BSL's Muslim Cha Quan root, it relies on large basic motions that can be shrunken to smaller ones in reality combat. Capoeira, Lama Fist, Tongbeiquan, and even savate have that "shrinkable" mentality for actual streetfighting that takes place at any conceivable range. All of these methods are fancy in training but become strikingly plain and subtle in real fights.
Most chinese arts or at least forms were developed before modern point sparring. Of course I do not include the Wushu performance forms in this group. Just about any art that uses forms has that large frame mentality except those that specifically claim to be small frame or small circle.
How does the Shaolin Temple's art, a chan buddhist temple, come from a muslim root? Cha quan is just one of the arts that influenced the temples fighting style, if anything it's root comes from your favorite, the five animal follies. Other arts were adapted and added as they were "discovered" and catalogued by the monks. The Muslim Cha fist was more likely derived from muslim fighting arts mixed with information from the shaolin temple, then folded back in anyway.
I do agree with you on the point that they all become shorter in the path they follow, one of the great methods of developing proper jing over time and with continued practice.
The cool part about BSL is that it's one of the few kung fu methods that can do the moves from other styles. For example, there are Tae Kwon Do style sidekicks in the "Moi Fah" set right around the middle before one goes into the crescent spin kick. And not only can BSL be used for reality combat, it can be used for noncombative disciplines like dance (very similar to ballet) and even Ch'an moving meditation.
The versatility of BSL stems from the fact that it tries to do just about every human conceivable move. Thus the way one uses BSL is truly limitless provided that he learns the basics well.
Call me a kung fu snob, but BSL's root arts were actually the parents of TKD and many others. Considering that fact and the fact that the shaolin arts are repositories of "What works", it shouldn't be strange to see signs of other arts in the techniques.
Whatever works- works.