Master Race: While the Imperial polyspecificity (which is to say, by no means just the eldrae, so not exactly a Master Race) is by and large comfortable in its non-innate-we-worked-hard-for-this-thank-you-so-very-much superiority to damn near everyone, as per Superior Species and Can’t Argue With Elves, they really have no time for this sort of thing.
(I mean, yes, obviously the universe would be better off with them running things, in their inimitable hands-off style, so everyone can and should look forward to the day when they attain this state philosophically through sheer force of virtue and arete, but one would have to be a pretty inferior superior species not to recognize the inherent paradox in going around conquering people in the cause of liberty, consent, and a-sword-is-not-an-argument rationality.
See also, to quote myself, “What sort of pathetic excuse for a Superior Race has to actually keep the Inferior Races down? Newsflash, morons, that means you weren’t qualified for the position in the first place,” and likewise, poncing around like a bag of giant fascist dicks also means You Fail Ethical And Intellectual Superiority Forever.)
((The irony, of course, is how many people find that attitude even more infuriatingly smug than, y’know, actually being conquered.))