not necessary
could be interest
plus at many IITs (not sure about K) the original major is only about 35-45% of the courseload
20-30% is quite flexible
advantage of light major- focus fully on the flexible part only on courses of your liking
not easy to do this in EC,MA,CS
He took civil engineering at AIR 179 , at this rank he could have gotten CSE at IIT kanpur , fear of ai is real