Look at the Wing Chun wooden dummy. Really stare at it.
Look at the length of the arms. Look at that leg. See how short they are from the body of the dummy.
'That' short, means it's a short range system and most of the moves, (not all), in the 108 reflect that you will be in this short range. (Only the kicks on the flank are where disengagements in that space occur - but you come back in).
So what ? The forms leading up to this 108 set are now being deployed with more footwork. You are in a showcase now of what fighting may look like, to a degree, in this optimized set of skills. When you specialize you leave things behind. This system has voluntarily left behind the long range kicks - it hasn't got any. This means it doesn't want you to get into a long distance game. No kick-fencing. It does give you tools to smother long low kicks, however. It does know 'others' do things that way.
Also in the form there are no long range punches. The arms partly influence this. They are so short, you have to do a calculated shuffle if you want that in. Look at the Choy Le Fut dummy. See how long the arms are on that - the central movable one. That is designed that way, as CLF, as long range aspirations in it. Design means intent - or at least it used to in the Middle Ages.
All this tells you of the design assumptions in Wing Chun's aims and optimizations. It has a small content because it only specializes in a limited range. THAT is its specialty. IT didn't claim to do anything else if you ask me. (assuming we have the perfect knowledge set of 'Wing Chun'), then it is a deliberately limited art to get you up and running. THAT story of Beautiful Spring time is to reinforce that point. SHE had a short term goal that needed seeing to. To 'sort out a bully', in a short time frame. Things had to be excluded.
The 108 repeats and drills many shapes and explores different scenarios of a 'small' array of moves in a short space.
Carrying on from this I would not even bother getting dragged into 'is Wing Chun good for sparring with'. No, it isn't as that uses space tactically - back and forth - and kick boxer / boxers have different appreciation of that space in sparring.
In its optimised space - if you can get the other person in that zone - that is what Wing Chun is for. Wing Chun is good at what Wing Chun specializes in. Pull it out of the ideal shape and its less useful. That is why I would not get pulling into, a verbal debate in the same way. That too, is out of range, by design. If you bring Wing Chun into different terrains with claims for it, then its a pain. You have to show how you can fight with others in different ranges in your ideal structure, (that makes it Wing Chun still and not become de facto kick boxing). Or you have to cite others who can - and this leaves you in a virtual world of possibilities not your own experiences. So don't bother. That argument is out of range too. Stay away from that and 'stick' to the aims and claims of 'the design'. That dummy is the design.
Short aims. Short arms. Limited content.