First of all the soviet had long range bombers in their inventory, both prior and during WWII, but to answer the question fully we must consider how the strategic aviation was seen in the USSR, how the VVS was organized and its experience.

Prior to 1939 the soviet long range aviation consisted of bombers that were designed for long range endurance flights, and so they were lacking in any other aspect like operational ceiling, speed and carrying capacity. These were because at the most part prior to WWII the aviation record braking was seen as a testament of soviet advancement and industrialization, so bombers were designed for that purpose.

In addition we must consider the experience the VVS had to that point. From its inception and until WWII its men fought in the Spanish civil war and ind the russo-finnish war of 1939. At these conflicts strategic aviation had a hard time finding good targets to attack and therefore had little effect. During the Spanish civil war the Luftwaffe found itself in the same position, so both of these air forces focused on tactical aviation.

The third aspect that applies on aircraft production during the war itself was attrition. The soviet rate of loss was staggering really, so much of the time the soviet aircraft industry was struggling to produce airframes with high attrition rates, to fulfill the Stavka demand for strategic reserve quotas.

With all of this the Russians did manufacture long range bombers like the Yermolayev Yer-2 And Petlyakov Pe-8, but they were few, and were rarely used in purely strategic attack role. The soviets relied on the americans and the brits to destroy the german industry with their massive bomber force.