Can a Higher Blade Help Prevent Kickback?
I believe that using a fully raised blade on a tablesaw can help prevent kickback. There are three reasons for this. The first is the direction of the cutting force. With a blade fully raised, the cutting force is down towards the table, instead of forward towards the operator. This helps keep the wood pushed more firmly on the tabletop instead of pushing it towards the operator.
The second reason is that fully raised blade reduces the size of the danger zone (shown in red in the diagram) between the blade and the splitter. It's that area where the splitter is ineffective at preventing kickback. With the blade lowered, this area is increased significantly. In fact, Europeans use a riving knife instead of a fixed height splitter which raises and lowers as the blade does keeping the danger zone at it's minimal regardless of blade height.
The third reason is the number of teeth that are in the wood being cut. With the blade fully raised and the cutting angle is down towards the table, the number of teeth that are in contact with the wood at any point in time, both in the front and in the back of the blade, is minimized. With a lower blade, there are more teeth contacting the wood, and each tooth travels farther through the wood.
Some may argue that having more blade exposed increased the risk of injury. Well, if you use a good blade guard it makes no difference. And if your fingers ever did get that close to a spinning blade, it probably doesn't matter if it's raised halfway of fully. If they are that close you'll probably loose them regardless of blade height. And if a fully raised blade scares you a little more, that might increase your respect and awareness and might make you safer woodworker.