Why Are Florida Homes Made of Concrete Block? 

Great information. I didn't know about the 50% rule.

I lived in a Cinder Block home during Hurricane Charley. The only damage was, roof panels, and the Metal Shudders had indentions from debris the F-0 that decided to breeze through the Yard.

You are a lucky man

why aren't there more icf houses?

For south Florida yea but not necessarily for northern Florida.

I know for a fact that concrete blocks don't insulate worth a damn. I am in Canada and at -30 C the concrete is a conductor of the cold and in summer it conducts heat. Even if you fill up the voids in blocks , there is still a cement connection a couple of inches thick. In Canada you would see the frost outline of this on your interior wall. 2X6's are the best and the wood is 1 1/2 inches wide but still wood is a better insulator than concrete. I put R20 insulation in the walls and 2 inches of SM on the outside for R30 walls . In Florida brick construction , you would be lucky to get R3. In Florida they also only have single pane windows. I use triple pane low e with argon gas. Bricks might be more sound proof but sound travels more through the windows than the walls. Unless you are in an apartment block, houses don't make a bit of difference with interior sound, wood or brick, so that is not an issue. People in Florida don't really get extreme temperatures so they don't know how concrete conducts heat/cold, they have had no experience with this. My basement is cement 8 inches thick and if I had no insulation , then the concrete would be very cold in winter. In summer it draws the cold from the deep ground and actually helps to cool the whole house. So it has zero insulation value. So I put 2 inches of SM on my basement walls 8 feet deep into the ground and on the inside I insulated the walls with R10 SM. So I have R20 on my basement walls. I also put 3 inches of SM insulation under my garage floor , so I heat the garage in the winter and the concrete stays warm. I think that the brick construction in Florida should sheath the houses in insulation from the outside, this would keep the walls at room temperature and you would not get the bricks expanding and contracting everyday with the heat cycle. Concrete does expand and contract with temperature, so does wood. In the winter the wood in my attic shrinks and I get a fine crack in one of my bedrooms upstairs and in the summer the wood expands again. Most people do not know this.