The converging of the feet in Wing Chun is often overdone, or practiced with little understanding of the reasons for it.
The feet are not pointed in for the sake of pointing them in. This is only a side effect of spiralling of the legs. As is the case when performing Tan Sau, spiralling is essential in our stance.
This is logical in a Martial Art that specialises in short range power. When big swings of the limbs are not possible because of space restrictions, the power must be stored in a more compact form – i.e. The Spiral.
A good spiral will have a counter spiral, which means that the converging of the feet will be very subtle. At a higher level, it will be invisible.
Too much converging of your feet means your counter spiral, and thus your storage of energy, is inefficient.