In an ideal world names would not matter, and the ideal behind the celebration would be of significance. We would all know why we were celebrating what we were celebrating. Sadly, this is not the case.
A couple of years ago, at work, I was asked why Sikhs celebrated Diwali despite not 'believing in' Rama and Sita etc. This did shock me, as until that time I was unaware that the knowledge of Bandi Choor Diwas was not infact common knowledge among Sikhs.
Bearing this in mind, and the confusion in Sikh minds regarding the puropse of the celebration, I think it has now become a neccesity to start calling the festival Bani Choor as opposed to Diwali, as the latter has created certain misconceptions.
While the name change is not inherently important to those of us aware of the real significance of the celebration, it has nonetheless become a neccesity as many are uncertain of this significance.
At the very least, if the festival is reffered to as Bandi Choor among Sikh circles, at least it would push people to question what this name actually means, and who was released and why. In this amnner, the 'new' name for the festival can act as a tool for educating those of us unaware of the real significance of this day for us.