The Russians follow different rules of engagement compared to ours. The Russian Sukhois have different roles compared to our Sukhois. The Russians have Su-27s and Mig-31s for air superiority, Su-34 for strike, Mig-25 for recce, Su-25 for CAP etc. Each fighter has a role defined. If you are fighting the Russians you will know for sure which plane will do what. If you see a bunch of Su-27s flying around you will know for sure they will not hit you.
It is not the same with IAF. IAF asks for Multi role aircraft. We need one plane which can do Air superiority, strike, CAP and Recce using one platform. This requires one man behind navigation, target prioritization and other aspects while the other one does the flying and shooting.
The WSO(Weapon Systems Officer) will prioritize an aircraft, a SAM system and stick a camera out to click pics of tank formations while the pilot is killing the targets assigned. In long missions that can stretch for 10 hours of more. The WSO can take over the controls while the pilot goes to sleep and vice versa.