As a less morally fraught example, consider the reaction you would have if it was exposed that your browser was secretly sending your passwords in plaintext to some third-party service to check if they were secure enough. It doesn't matter that helping users avoid weak passwords is a noble goal and genuine objective; sharing users' passwords like that is completely unnecessary and thus indefensible.
The question then becomes: was there a better way to achieve the "good" of the colonial era - technological progress, etc - without colonisation itself? And the answer is yes, absolutely 100% yes. Colonisation was a betrayal, not the start of Europe's history with Africa and Asia. To give an example close to home, the Portuguese and later the English had a fairly balanced mercantile relationship with the Benin Kingdom (part of modern-day Nigeria) for centuries before the British colonial expeditions of the very late 19th century. You can even tell from the words of earlier visitors/tourists like Olfert Dapper that there was a respect for the people, their way of life and accomplishments (the Edo people were quite good at architecture, for instance).
The Benin Kingdom could very well have continued its natural technological, economic and social progression with the support of non-violent foreign partnerships and trade while retaining its sovereignty, but for the greed of the British. In fact, colonisation has most likely hampered its development, not accelerated it. Japan for example avoided colonisation entirely and has quite clearly caught up to and surpassed its near and distant neighbours that got that dubious "help". Or consider how quickly Hawaii modernised even before it lost its sovereignty to the United States.