It is an important piece of the puzzle , but it is only one piece of the puzzle.
Sparring in chi sau , is training for close range combat , where the sense of touch becomes more reliable than vision.
It's definitely not the only type of sparring you should be doing , you should also be doing hand sparring from your Wing Chun guard vs Wing Chun guard , so that you work on your visual reflexes and Chark Jong (smashing defences) before contact is made.
Easiest way to do that from chi sau is to practice breaking off and re-engaging again.
You should also be doing a fair bit of stuff like four and six corner deflection against non Wing Chun punches , as well as working on your leg defences against non Wing Chun kicks , you can mix it all up together in an exercise we call "random arms and legs"
Chi sau is a great tool , but we have to get past the pre contact phase intact first before we can use it , which means that when the opponents hook comes rocketing in at a great rate of knots we have to rely on our eyes to see it and make sure that our arm is up where it needs to be to intercept it.
I agree..do you have a video of your exercise " random arms and legs"?