When raising the food the cat has a better position when eating because gravity helps to get the food down to his digestive system.
This is especially important when cats have some medical conditions in their esophagus that makes swallowing hard creating re-flux or vomiting in some cases.
Elevated Food also allows the cat to relax its body when eating. This is especially important in old cats because sometimes the stress in muscles, bones, or joints does not allow them to eat very much, which means they are not getting all the nutrients they need to be healthy.
In general, elevating the food and water bowls helps cats to reduce the strain when leaning their bodies, which helps to avoid future problems in the spine, hips, or digestive system.