Requires more training to manage the wing sweeps for the different flight regimes.
The mechanics driving the sweep also take up extra space and weight.. and are prone to failure.
later mig-23 variants such as the MLD-K used an automatic sweep system.
hey thanks! I'm bit occupied these days, also avoid other forums as too much bickering goes on and im tired of chinese narcissism and them getting leeway of india bashing at every issue!