And I'd say again that I don't consider Remington indicative of the industry as a whole. As far as problems on a "statistics" basis, my undergraduate degree is in applied math statistics. There is nowhere near enough information out there, imo, to make judgements on firearm manufacturers as whole, especially if we want to establish a trend over time as problem reporting before was limited to telling your buddies at the gun store.
For that matter I will still argue that Glock from Gen 4 onward has had numerous issues, including a rash of ejection problems that may have gotten better but continue to show up on forums (including here). To me the anecdotal information out there, and that's what it is, doesn't really support that these days Glock is significantly better than the competition when it comes to out of the box reliability. My point here isn't to pick on Glock. My goal is to point out that given the anecdotal nature of any evidence of issues declaring one company better, or worse, isn't particularly easy. And then we have to factor in production numbers as well.
You keep pointing to Remington, but my argument would be Remington is a statistical outlier in just how bad it is. Pretty much any company compared to Remington currently would have better quality control.
As far as Toyota not blowing minds at trade shows, Toyota has been a leader in hybrid cars for years. To the point where even new hybrid cars struggle to match the performance of the Prius (a fact that still baffles me). Toyota didn't just rest on their laurels. They continued to innovate and to me that's part of the reason for their success. I'll again bring up Colt. Colt is absolutely a company that kept to its core products and while they had stumbles over the years when it came to a 1911 or AR they were bedrocks people would point to. Colt declared bankruptcy not long ago and it wasn't the first time. I get what you're saying about keeping core products strong, but I think you're still missing why these companies are expanding their lines.
The CZ P10c is to me indicative of a consumer market that despite being disappointed in the past by early rave reviews refuses to learn a lesson. I find it crazy how people have essentially crowned it as almost the king of striker fired pistols based on what are some initial reports of pre-production models (not you specifically but online it is brought up constantly). Yes they have made good pistols in the past including a striker fired pistol. But their reputation was built on hammer fired DA/SA pistols. It would be like me saying Chevy is going to produce a great compact car based on me owning and liking the Silverado. I think the enthusiasm has more to do with people eager for new products than a basis in reality. In a year we can judge how the P10c is doing, but the amount of fanboys it already has is a bit nuts imo.
I'm NOT saying that companies should not innovate, create, or diversify. I'm saying that they shouldn't sacrifice the quality of their already successful models in order to bring out the next best thing.
My whole point is, I think some companies have lost that trust with consumers (or at least with me). And I think the reason is that they've compromised their "key" products in a race to come out with the latest and greatest thing.
I would again state that you're underestimating how important new products were for a number of these companies. You've already admitted that these new products likely kept a number of companies in business. You keep saying you're not opposed to innovation and new products but then keep pointing to gun companies that haven't produced new products as the standard and blaming the failures of a number of these companies on the desire to have new products.
To go back to Remington, that is a company that has been failing for a number of years now, since well before the RP9. To me even if they hadn't produced the RP9 they would continue to fail. They've fallen by the board far more than any other manufacturer I can think of. I don't see them righting the ship any time soon, perhaps ever.
While there are plenty of people that prefer the older S&W revolvers and the German P series SIGs, to me those product lines haven't been nearly as tarnished in reputation as say Remington nor do I think on the whole they're as bad as some claim. And I honestly don't think those bad examples from S&W and SIG are because of them making other products. I think it has more to do with an industry that produces far greater quantities than it did before and is rushing to get everything out the door. I think you can have a diverse product line and produce quality products. And difficulties while bringing a new product line up to speed aren't uncommon but don't have to be permanent.
I also question whether things are really that much worse for a number of companies, or we're simply more aware of it both because of the sharing capabilities given to us by the internet and simply because of the much greater quantity, not just diversity, being produced today. Even if I only had a 1% QC issue rate, if I produce 100 pistols a month that means 1 is bad. If I produce 10,000 pistols a month that means 100 are bad. Given the lack of actual data from before I don't think you can ignore these factors in the overall impression of the state of QC of the industry.