If independent India could send a space probe to the Moon, surely it could reform its legal system as well. Vast majority of Indians alive were born decades after the Raj ceased to exist.

Usually, when such old structures survive, it is because of concrete people and interest groups who want to keep them alive. And this is more of a domestic problem than a (ex-)colonial one.

In my country, compulsory identification cards were introduced by Nazis during the occupation. All subsequent regimes, including the democratic ones, kept them: too useful to scrap. But it would be misleading to say that we can "thank" Hitler for having cards in our pockets. We could have scrapped them if we wanted to, like we scrapped many other regulations and laws from that cursed era. We didn't.