Question

Are our wisdom teeth relly use full for chewing the food

Answer 1

Anthropologists believe wisdom teeth, or the third set of molars, were the evolutionary answer to our ancestor's early diet of coarse, rough food – like leaves, roots, nuts and meats – which required more chewing power and resulted in excessive wear of the teeth.

now we don't need it because we can cut, dice, chop, boil, steam, and bake almost everything we eat.
thus they are removed

Answer 2

Wisdom teeth are a remnant of a past(~100 million years ago) where a third set of molars was required to offset the wear and tear of our ancestors’ teeth. Their diet consisted primarily of roots, leaves, nuts and tough meats, which are very coarse foods requiring a lot of chewing. Also their jaws were much larger, they were still running around on all fours and teeth were extremely important in grabbing, tearing, even dismembering prey. Wisdom teeth were sort of a backup set of molars that would appear sometime after they were 17 (life expectancy was barely above 30) to ensure that they did not starve to death because they could not chew their food anymore.

Fast forward to now, where our diets consist primarily of much softer, cooked and processed foods - infact we don't need teeth at all. We have to get our wisdom teeth removed because our jaws have evolved and cannot fit in 32 teeth anymore.
but if we keep our teeth neat and clean by brushing twice in the morning and night then we do not need them