If the spices are compatible with their system, one can go for spices. Climate plays an important role in Spicy foods. For a country like India, one has to exercise utmost caution in using them sparingly. Over use may lead to health complications.
Because of the tradition. We have lot of poojas and we prepared lot of foods to god. So they use pepper, ginger, cardamom, turmeric,clove. After the rule of Sultans our taste buds are completely stick with the taste of Biriyani. Now it is anytime receipe in the tv shows. These are not the only reason but we the uses of it and we practising.
Spices have natural nutrints. These spice add not only taste to the food but also supply required nutrients for the body. But these spices should be consumed in a balanced manner. Else they will be counter productive.