A combination of several things.
The Soviets had a much smaller need for a surface fleet of any kind. Simply put any war would be decided on the Eurasian landmass, meaning the USN had to secure sea lanes and project power, while the USSR only had to deny and degrade that. That meant that subs worked just fine for them. When they did get into the power projection game they really had very little to base it on, so they really just went with what they thought would work, some were intimidating if over built like the Kirov's, and the Kuznetzov's but by that point in the 70's and 80's there was never really any hope they could catch up to the US in proficiency with carrier operations.
The USSR really didnt have any tradition of a strong surface fleet, and despite Stalin's plans for a blue water fleet, they built some damn good subs by the end focused very much on them. In fact really Russia hasnt had a great history for a few centuries with naval power, including being just embarrassed by the Japanese in 1905 in the Russo-Japanese War, and the effect it had on culture was lasting.