I don't think anyone thinks it was a superior way of life. Marxists are modernists, they want technology and societal advances like everyone else. The point is just that it demonstrates that "human nature" is malleable.
That said, there is some evidence that in some respects it was superior. Hunter gatherers have more leisure time and agriculture, IIRC, had immediately negative effects on human health because of the extra work involved and the suddenly much less diverse diet, leading to malnutrition, stunted growth, etc., but it was worth it because of the stability that it afforded once people really got the hang of it, job specialization, etc. At the same time it also led to more oppression and warfare because of the rise of states. So there were tradeoffs in both directions.
From what I recall agriculture was experimented with during the Mesolithic but really took off during the early Holocene because of climate fluctuations causing people to fall back on it in the lean times, and then they just continued developing it from there.