Most of us?? what an extraordinarily bold generalisation.
I have no objection to the temporary marina, as many of the users would appear to be coming from overseas, and this is good for the tourist trade, the economy and jobs. Most of us will probably be letting our homes for the Olympic weeks, and taking holidays on the proceeds, so we won't be here to see it.
However, a permanent low cost shanty town on water is a different matter and should be opposed on the grounds that it will bring our property prices tumbling down amongst many other reasons.