Our body is made up of organs which interact with each other to keep it healthy. Food provides necessary nutrition to keep our body healthy. Salad contains good amount of nutrition in form of minerals, vitamins.
If a person's traditional(comes from culture) food habit contains enough vitamins and minerals, then salad becomes optional. Consider traditional south Indian food including Sabar, Rasam, Pickle, Papad, chutneys and leafy Daal. Note that these menu has good amount of minerals and vitamins. This is the reason why traditional south Indian meal doesn't insists on eating salad.
In contrary, western/ American typical diet doesn't include enough minerals/vitamins. In this case, Salad is a healthy way to provide enough minerals and vitamins.
In this case, you should be worried. Try to change the food habit. Alternatively, there are good plant based health supplements available in market. Your body will receive these supplements as food. And eventually, it will make you healthy
http://www.slu.edu/nutrition-and-dietetics/blog/blog-spices-and-herbs-that-are-missing-in-the-western-diet
http://www.academia.edu/2054892/MINERAL_NUTRITIONAL_STUDIES_IN_ALLSPICE
https://bewell.stanford.edu/health-benefits-herbs-and-spices
http://www.nutrilite.com/