The perceived 'hate' is a result of two things;
1) Germany seems determined to drive them out of business (they darn near can't export any products now, and it's been getting increasingly bad for decades), and America has burned their civilian sales
specifically at least a handful of times in the recent past. 922r was written almost explicitly with the roller-locked G3 rifles in mind (as well as FN FALs), and we repeatedly screwed over the various Euro makers during the 80's under Republican presidents (then everybody else with a Democrat president)
2) HK has an extremely aggressive marketing strategy (they're practically the Apple of the gun world in this regard) wildly out of proportion to their market share, which attracts civilian interest just as effectively as LEO/MIL interest, since both groups think the same guns are cool (or alternately, civilian tastes imitate professional ones). Their stuff has been ubiquitous in civilian media like movies and video games for decades, which is flatly illogical if you think about it (not all of it is HK's doing, but I have to imagine they pay to get their stuff in video games, considering how constant their presence is)
The result is a sad tale of star-crossed love, where the cloistered HK in its ivory (plastic) tower and we mere civilians gaze longingly at one another and wonder what might be...
That HK also makes/offers some ridiculously boutique guns like the MP7 and sells a catalogue that is quite rife with cost-inflation generally, leaves them with an image of needless prestige and luxury which infuriates us unwashed masses further.
Now, recent events are possibly changing that state of affairs. If the G36 failure ends up being what I think it is --that HK recklessly substituted inferior materials into their products under the promise of political backing to their denials-- their attitude really does become one of utter arrogance.
TCB