well, you have to remember we're dealing with the laws of large numbers, not rating specific houses for their specific risk. In fact, some people would get payments from a policy after a flood and rebuild 3, 4, or 5 times in the same spot, with no (or little) change in rates. You can see how that screws everyone.
the flood insurance program is run by the federal government, and as such is extremely reactionary and sometimes outright incompetent. Prime evidence is the recent change. The rates certainly needed to change, because the flood program is straight up broke, going all the way back to Katrina. People (unfortunately like you) insuring homes in high risk and super high risk areas were paying subsidized (by taxpayers) rates, meaning no one's ever actually seen the true cost of insurance. The other problem was with homes built before the Army Corp created the flood maps (and the flood program existed). All those homes (built before the mid-70s in most cases) were rated differently, typically MUCH lower than if they had a newly-constructed home, thanks to grandfathering rules. Another fun rule said that 2nd homes and rental properties were given cheaper rates than primary homes (for some reason?).
I think most of these rules were meant to keep people in their homes and to promote development of otherwise risky areas. As with most federal programs, it's now fucked and we all have to play (pay) catch-up.
You made an excellent point about coastal property values (and property values for homes along rivers and in other flood basins). It's a looming problem that the government didn't seem to consider. Or if they did, they decided that the change had to happen and the pain was going to be there anyway, so let's go cold-turkey. As I said before, it took about 8-9 months to interpret only about 60% of the new law (as of Sept/Oct 2013), so there will probably be more updates as we go.
I know real estate lobby groups are on it and the senate has already been holding hearings, so things will probably change again. In the meantime, you're going to be out of luck. Coastal regions are difficult but I would recommend you investigate flood mitigation updates to your home, if any are possible. Depending on the construction and location, you may be able to re-qualify for prefered rates instead of the standard rates, though I'm not as familiar with coastal flood rating as inland.