The AK-74 was introduced to replace the AK-47 and AKM for several key reasons, primarily revolving around improvements in performance, accuracy, and adaptability to modern warfare.

1. Caliber Change: The AK-74 was designed to fire a smaller 5.45x39mm cartridge, compared to the 7.62x39mm round used by the AK-47 and AKM. This change allowed for a lighter rifle and ammunition, which improved the soldier's load and allowed for higher ammunition capacity. The smaller caliber also resulted in reduced recoil, enhancing accuracy during rapid fire.

2. Improved Ballistics: The 5.45x39mm cartridge offered better ballistic performance at longer ranges. It was designed to be more effective against body armor and to have a flatter trajectory, making it more suitable for modern combat scenarios.

3. Weight Reduction: The AK-74 was lighter than its predecessors, which made it easier for soldiers to carry and maneuver. This was particularly important in the context of modern warfare, where mobility is crucial.

4. Enhanced Accuracy: The design of the AK-74 included improvements in the barrel and sights, which contributed to better accuracy. This was essential for engaging targets at greater distances, which became more common in the conflicts of the late 20th century.

5. Adaptability and Modularity: The AK-74 was designed with a more modular approach, allowing for various attachments and modifications, such as scopes and grenade launchers, which increased its versatility on the battlefield.

6. Soviet Military Doctrine: The introduction of the AK-74 aligned with the Soviet military's evolving tactics and strategies, which emphasized the need for a weapon that could perform well in diverse combat situations, including urban warfare and engagements at longer ranges.

Overall, the AK-74 represented a significant evolution in the design of assault rifles, addressing the limitations of the AK-47 and AKM while adapting to the changing nature of warfare.