Abundance is an idealistic notion. There are also problems with the way Marx defines value. Marx wishes to measure the value of commodities based on the amount of labor that goes into producing them, rather than the useful ways the commodity can be used. A third flaw in Marx's logic is his allusion to a system in which authority is unnecessary. Someone must make sure that work is done, and done well.
Authority is necessary for a system to run.
Marx highlights many problems with capitalism, but he does not offer an alternative. Therefore many attempts to interpret his doctrine and plan a socialist economy have failed. I think Marx differed greatly from the utopians in his ideas about how a socialist utopia should be reached. Well, lets start with the last question first. The free spirited beliefs that the honest worker is the heart of it all, and that any human realation should take place above and beyond the state were nice, but not grounded in any theory that would elevate the situation beyond what it was.