Fujii,
Thats right. This would not allow for a coastal transit without a clearance. It would however allow for a very easy inland transit.
This is one area where the whole rule situation needs to be taken into account. In the USA there is no requirement under part 91 for lifejackets unless you are 50 miles off shore so a short diversion out around airspace can be done without them. See for example the lakeshore to the east of Chicago O'hare or south of JFK? Is the risk of an engine failure at the exact instant resulting in a controlled ditching so high that it offsets convenience of GA being able to move through major centres unhindered?