Class struggle doesn’t end in one stroke. When the working class wins state power over the capitalist class, the former doesn’t stop existing. The cudgel is to keep internal and external capitalists from counter revolution.
Ultimately, results matter. My country started semi feudal and it was under socialism that it industrialised, electrified, developed universal health care, built homes for every working family, etc. Sadly the coup in 89 ended that, but it doesn’t have to have been perfect to have been good.
My passport still says "place of birth: USSR". As a child, I lived on a street named after a prominent Bolshevik who was famous for using poison gas to crush a local peasant rebellion against the Soviets when they started to confiscate grain at scale to the point of starving whole villages out. Even if all the achievements you claim were true, the ends still not justify such means; but the achievements are mostly a lie anyway. Many other countries saw development from mostly rural to mostly industrialized during the 20th century and got all the benefits you described without a pile of "enemy of the people" corpses to go along with it, so socialism has very little to do with it.
FWIW I don't even think USSR and its satellite states were socialist in any meaningful sense. Socialism, after all, is the common ownership of the means of production. But most of the populace on all those states were excluded from governance, and thus from any effective ownership. So, in practice, it was collective exploitation of the workers by the elites under threat of direct physical force - strictly worse than wage slavery. Some orthodox opposition Marxists in USSR even claimed that it was the perfect example of what Marx originally called the "Asiatic mode of production".
Which country? 89 makes me think not Russia.. Romania?
It is worth pointing out your observation applies to lots of post-colonial societies, too. Socialism took Tanzania's literacy rate from about 10% at independence to 80%+ in a generation, and IIRC it also doubled its agricultural output in that time by organising farming along collective lines. Life expectancy rose substantially too, though I forget by how much.
(So much for empires being about spreading civilization, eh?)
Ultimately, results matter. My country started semi feudal and it was under socialism that it industrialised, electrified, developed universal health care, built homes for every working family, etc. Sadly the coup in 89 ended that, but it doesn’t have to have been perfect to have been good.