There was an outcry among the Muslim community in India against this ruling. I am not sure what the exact legal position is now in India in such cases, but Islam does not require a man to support a woman who is no longer his wife. In the Islamic family system, the woman should be supported by her own people, i.e. her father or her brothers, or uncles, etc. The point is that marriage is a legal contract. When it is broken, then all rights that have been established by such a contract come to an end.
Maintenance is one such right.
Your question is whether it is necessary that the couple should get divorced. The answer is that they know better. I cannot tell them whether it is necessary or not. However, in such cases, the Islamic view is that if the man and the woman want an amicable solution to their problem, then two arbiters, one from her family and one from his family, should meet to discuss matters. If an agreement is reached, well and good.