Beware the Nice Ones / Good is Not Soft: It’s not the most appropriate trope-pair possible for this aspect of your average Imperial; that would be Silk Hiding Steel (they’re bad at malice, on the whole, but they ain’t that nice). But the trope writeup pages each include this Discworld quotation:
“If you have to look along the shaft of an arrow from the wrong end, if a man has you at his mercy, then hope like hell that man is an evil man. Because the evil like power, power over people, and they want to see you in fear. They want you to know you are going to die. So they’ll talk. They’ll gloat. They’ll watch you squirm. They’ll put off the moment of murder like another man will put off a good cigar. So hope like hell your captor is an evil man. A good man will kill you with hardly a word.”
That. Oh, so much that. The eldrae in particular don’t really get the urge to rub power in people’s faces just to show you can. Power, maybe, nice to have, but if you’re going to exercise it, exercise it properly. If you need to die, they’ll just kill you. Without blinking.
(If they’re wasting time talking to you, it probably means that they fired already, and are just keeping you busy running out the clock until the KEW impacts.)
This applies on a civilizational level, too. The Empire does not have a large and potent fleet for the purposes of interstellar imperialism and making everyone else in the galaxy Do It Their Way. That’s rude and uncivilized and not their sort of thing at all.
It has a large and potent fleet for the purposes of ensuring that anyone who decides to interfere with its citizen-shareholders full, rich, happy, and carefree lives and is unwilling to be reasonable about not doing so gets a gigaton of pain for their trouble and are rendered incapable of ever doing so in the future.
(Actually, you can think of this as a canine virtue, if you like. Cheerful, lovable, friendly, gentle, affectionate, adorable… right up until you threaten them or someone/something they care about, at which time they rip your throat out. And then go back to being all those previous things.
This is considered something of a moral model.)