Being the colony of a powerful empire does has it's advantages but also brings with it a lot of limitations.
Colonization usually resulted in restrictions on freedom of speech as well as a control economic environment.
Many colonies e.g. the ones in the British Empire, were only allowed to trade with other colonies and not outside the Empire.
This greatly restrict trade opportunities.
Social restrictions of no voting rights and lack of freedom of speech, also gives rise to nationalist movements which can create further trouble.
Decolonization provides not only more economic opportunities but the chance for people of the country to develop their own rules and laws suited to their own customers and traditions.