I agree 100% that the EA community's efforts in areas like malaria and direct cash transfers are falling quite firmly within the 'elimination of concrete evils' camp. IIRC you differentiate between the philosophical foundations and actual practice of effective altruism in your essay. So even if most EA work currently is part of the aforementioned camp, the philosophical foundations might not actually imply this.

Hi, I enjoyed your article. Parts of this remind me of Popper's "Utopia and Violence" in Conjectures and Refutations. Given that (strong) longtermist philosophy leads one to consider the value of an action in light of how much it could help bring about a particular utopia (often a techno-utopia), you might find inspiration to expand your critique in Popper's essay. (I don't want to endorse any specific view here, I just thought this might help you build a better argument).

Some quotes:

That the Utopian method, which chooses an ideal state of society as the aim which all our political actions should serve, is likely to produce violence can be shown thus. Since we cannot determine the ultimate ends of political actions scientifically, or by purely rational methods, differences of opinion concerning what the ideal state should be like cannot always be smoothed out by the method of argument. They will at least partly have the character of religious differences. And there can be no tolerance between these different Utopian religions. Utopian aims are designed to serve as a basis for rational political action and discussion, and such action appears to be possible only if the aim is definitely decided upon. Thus the Utopianist must win over, or else crush, his Utopianist competitors who do not share his own Utopian aims, and who do not profess his own Utopianist religion.

But he has to do more. He has to be very thorough in eliminating and stamping out all heretical competing views. For the way to the Utopian goal is long. Thus the rationality of his political action demands constancy of aim for a long time ahead; and this can only be achieved if he not merely crushes competing Utopian religions, but as far as possible stamps out all memory of them. 

[...]

Work for the elimination of concrete evils rather than for the realization of abstract goods. Do not aim at establishing happiness by political means. Rather aim at the elimination of concrete miseries. Or, in more practical terms: fight for the elimination of poverty by direct means--for example, by making sure that everybody has a minimum income. Or fight against epidemics and disease by erecting hospitals and schools of medicine. Fight illiteracy as you fight criminality. But do all this by direct means. Choose what you consider the most urgent evil of the society in which you live, and try patiently to convince people that we can get rid of it. 

But do not try to realize these aims indirectly by designing and working for a distant ideal of a society which is wholly good. However deeply you may feel indebted to its inspiring vision, do not think that you are obliged to work for its realization, or that it is your mission to open the eyes of others to its beauty. Do not allow your dreams of a beautiful world to lure you away from the claims of men who suffer here and now. Our fellow men have a claim to our help; no generation must be sacrificed for the sake of future generations, for the sake of an ideal of happiness that may never be realized. In brief, it is my thesis that human misery is the most urgent problem of a rational public policy and that happiness is not such a problem. The attainment of happiness should be left to our private endeavours.