Economic Marxism does not get attention for two reasons:
(1) because it's an economic theory for late 1800 era society.
(2) It does not advance or develop. Something that revolves around interpreting "what Marx said" is not living economics. Most socialists don't think Marxism is good economic theory for working class anymore.
I think it's reasonable to say that Marxism continues to evolve as people continue to apply and evolve its principles to modern conditions. Just as capitalism has continued to evolve after the death of Adam Smith (although, to be fair, Marxism is more directly associated with its namesake).
As one example, Kohei Saito has recently published popular works of Marxist perspectives on climate change and modern capitalism. I'm no expert, there are likely other, better examples.
Capitalism hasn't evolved but rather "devolved" into Cronyism from a benign "invisible hand of the free market" phenomenon of Adam Smith and David Ricardo into a fully fledged corporate machine with tentacles into layers of political and media control.
But given the long-term trajectory of "free markets" and "invisible hand", I guess this was bound to happen at some point. I wonder what Smith and Ricardo would have said if they knew *this* was where their economic vision is going to end up!
Economic Marxism does not get attention for two reasons:
(1) because it's an economic theory for late 1800 era society.
(2) It does not advance or develop. Something that revolves around interpreting "what Marx said" is not living economics. Most socialists don't think Marxism is good economic theory for working class anymore.