Also, at the time there was a spirit of optimism around, Things had been gradually getting better as the devastations of world war were mended and conditions improved in most countries. It seemed that nations were learning to live together on peaceful terms (give or take a bit of posturing) and there were efforts to equalise the differentials between rich and poor. It looked as though those improvements were going to continue. It was worth branching out and doing something - something exciting for a change - that had never been done before.
We didn't realise then that human nature doesn't change, that greed and spite were waiting to be unleashed again, against people of other countries and people of the same country, indiscriminately, and seem more important than preserving the earth we had inherited and cherishing humanity in all its variety. Living well hadn't yet blunted the edge of concern for others less lucky. Temperature extremes and evil regimes hadn't begun to make some lands less pleasant to live in so that their inhabitants seemed to threaten to overwhelm the more fortunate areas and cause bitterness. Welfare budgets did not appear to be stretched to the limit.
You can't judge a past project by the arguments you would make against it now.