You know, most causes that US leftists ought to campaign for (before you can expect the rest of the US working class, who do not have the same understanding of the capitalist system as leftists, to get involved) -- from establishing socialized medicine to slowing down climate change to ending the US wars in Iraq, et al. -- are all "a waste of time," if you think that anything that you are unlikely to achieve any time soon is "a waste of time." (Abolitionism, to take just one example, must have seemed a waste of time for a long time by that definition.)
Now, a case can be made that all Americans can ever achieve is an empire with a higher minimum wage, better city councils, etc., (which may be true for all I know), so they should focus only on those. But there is no need to dress up that case in any Marxist theory* (which will detract from it anyway). You complain that activists do not take interest in theory, Americans are anti-intellectual, SEIU doesn't campaign for socialized medicine, and so on and so forth, but perhaps they don't want theory or intellectuals or a campaign for socialized medicine for a good reason -- such are a waste of time for them, just for the same reason that you think a lot of things are a waste of time.
* Granted that Marxist theory minus transition to socialism can be useful to deceive oneself as well as others outside the North. One can quote Marx, Lenin, etc. selectively to say, "See, Marx and classical Marxists were all in favor of capitalist development! Don't worry about climate change and other environmental damage! Peasant life is a backward life, so let's liberate small farmers and agricultural laborers from the idiocy of rural life! We can build a factory on the land expropriated from them, and they -- or at least some of them -- can become wage workers at the factory, which is decidedly a step up, especially for women."
"In Russia, Marx's Capital was more the book of the bourgeoisie than of the proletariat." -- Antonio Gramsci, "The Revolution Against 'Capital'," 1917 -- Yoshie