One might argue that they have a history of putting out *crap* products too, like their old HK4 (cheap Mauser HSc copy made of stampings) and polymer VP70Z. (with terrible ergonomics and one of the worst triggers to come down the pike.)
A case in point; great big 9mm "pistols" don't sell well . . . even the famous "UZI" didn't do too well in "pistol" form.
And their HK416/MR556 - another piston driven AR clone - is pricey even compared to other quality rifles on the AR platform, besides being late to the party. I will say, their current USP-series guns seem to work well, but they're a bit on the bulky side.
Their perceived "Because you suck and we hate you" attitude hasn't helped, either . . . Americans don't respond well to this kind of Teutonic arrogance, especially when there doesn't seem to be that much for them to be justifiably arrogant about.
I've never heard any complaints about the HK4, other than it was too large for a .380 or .32, much less a .25 or .22, but it reflected the waning but still dominant European pistol culture that considered .32 and .380 "service calibers" while American gun culture pretty much considered them BUG/pocket-gun calibers.
The VP70z (zivilian/civilian) did indeed have a horrid trigger, but of course that's because it was made to be a FA SMG with a dual semi/FA trigger pull with the pistol stock holster engaging the sear. They were trying to leverage the polymer frame as cost savings, intending it to be sort of a 1980's STEN that West Germany could stockpile for the populace and police to help fend off a Warsaw Pact invasion through the Fulda Gap etc. HK never really intended to sell the z model as a direct marketing idea. They had the tooling, so decided to ship some to America and see if they'd make any money.
Of course they didn't, but it's not like the VP 70 was a stand-alone concept they had tried.
The HK416/MR556, as far as I knew, it was just an intentional act of bone throwing to the American civilian market. I doubt they made any money on the number of them they released.
I'll agree that there has been some actual "Because you suck and we hate you" from HK over the years, but I'd say 5% of it was actual "tude" from the company, and 95% buthurtedness on the part of the American shooting market blaming HK, when the deck was almost always stacked against HK's products economically or legislatively. (GCA '68 "import points". Bush '89 import ban, '94 AWB... P7's being too expensive to machine and hand-fit due to it's design, despite how much they were loved by their fans... etc.)
During the entire civilian "golden age" of HK civilian products, they also got SPANKED by domestic U.S. arms. An HK93 in 5.56 was something like $900, when AR's were $200-300 cheaper, the Mini-14 $500 cheaper. The SP89 "pistol" was $600 or so, when a $300 Ruger could hold as many rounds and had much cheaper magazines too.
And the tacticool market was a lot smaller then. The ten years of the '94 AWB, and the expansion of CCW that made America lust after "tactical" firearms as arguably the biggest market segment hadn't happened yet.
Not to mention, like water, market forces and opportunity costs always flow to the cheapest point, even when you wouldn't think certain items weren't even in direct competition. $300 MAK 90's, and $50-99 SKS's by the barrel were being sold in gun stores side by side with the HK products too.
I guess one could argue that a TRULY committed, innovative, and aggressive company would have figured out ways to overcome all these things, but HK always had a stacked deck against it in the U.S. civilian market, either in terms of timing, money, or regulations.
