All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we should say that it is an obligation to accept the laws of Allaah whether or not we know the wisdom behind them. When it comes to accepting the laws of Allaah, suffice it to believe that Allaah is Most Knowing and Most Wise and that all of His actions and judgments are based on wisdom. We should believe that we only know very little, and that we are unable to comprehend the circumstance around us. Allaah draws our attention to this fact in the Quran, namely that He knows and that we do not know, in five places; Allaah says (what means): {And Allaah knows, while you know not.}[Quran 2:216] [Quran 2:232] [Quran 3:66] [Quran 24:19]. And Allaah also says (what means): {Indeed, Allaah Knows and you do not know.}[Quran 16:74]
Nonetheless, it is permissible to reflect over and seek the wisdom behind certain laws, but only after conceding the named fact and harboring doubts about the laws of Allaah or being discontent with them. The right intention for trying to understand the wisdom should be to increase one's faith and glorification of Allaah.
That said, we would like to add the right to inheritance is not related to how great a role one plays in the life of the deceased, because if this were the case, the wife would not have right to a greater share than the mother, who bears the child and suffers the bitterness and difficulties of pregnancy and raising the child. Yet it is known that the wife takes a greater share than the share of the mother in some cases. For example, if a person dies leaving a wife, a mother, and three or more full brothers and sisters, and does not leave any other heir, then his wife gets one-fourth of the estate whereas his mother gets one-sixth; and the brothers and sisters get the remainder. The share of the wife here is more than the share of the mother, and more than each single brother or sister. If the determining factor for who gets the greatest share was how great a role one plays, then the wife would not have the right to a greater share than the mother.
Furthermore, if the role was the determining factor, the mother would have rights to a greater share than an infant child of the deceased. If a person dies and leaves behind a wife and a baby who was born a few hours before the death of his father, then the wife of the deceased takes one-eighth and the remainder is for the baby despite the fact that the baby did not play an important role in the life of his father - contrary to the wife; so whoever plays a greater or important role is not a determining factor.
In addition, when a wife plays an important role in the life of her husband, she does so in return and not for free, as he provides her with food, drink and clothing, and keeps her chaste. So, she should not neglect this reciprocation. Also, even if we say that the wife plays a greater role than the brothers and sisters, we ignore at the same time that the brothers and sisters in principle are closer to the deceased than the wife, as they are created from the same water - from the same father or mother - whereas the wife is a stranger to the deceased in principle. In fact, were it not for the marriage contract, she would not inherit anything as her husband could have divorced her during his life with one single word. Indeed, Allaah has spoken the truth as He says (what means): {And Allaah Knows, while you know not.}
Allaah Knows best.