Residents of Reunion Island have to actually provide their biometric data and have their photograph taken at a visa application centre. They can provide their biometric data in any country or visa application centre. They don't have to travel to Paris. The closest centre to Reunion Island is in Mauritius. To get there, you have to take a 45-minute flight and spend a few hundred dollars. However, I agree that this is an additional step that residents of Reunion Island must take in order to hope to study, work or immigrate to Canada.
Canada could consider opening a visa application centre on Reunion Island. However, we need to see how many applications there are and whether it's profitable for private enterprise to open such a centre on this island. I know this was studied in the past, and the number of requests proved insufficient.