This question in itself is a controversy. Who decides what is better for a society? In Things Fall Apart, we see a culture changing because British missionaries and eventually British culture move into and change the Igbo community. Make no mistake that the culture and people had their own set of rules to abide by and punishments for those who refused to comply. What we see is a change of those rules and a different attitude towards punishment. Peaceful would be questionable, but as far as society being better off........ what society doesn't benefit from technological advances? In essence, I think it's pretty much a mixed bag. Religion is of utmost importance, missionaries provide spiritual guidance, education, ect., ect., but British rule (or rule by anyone for that matter) doesn't necessarily mean that anyone is BETTER OFF.
Destroying a culture is a travesty, and in this novel as in many other instances throughout history...... cultures begin to disappear.