Idk, this was after they were banned by the FAA, so I don't think it was a "PR hit to attempt to maintain quality," I think it was to stem the damage. The Note 7 was already in the news by that point, and 3 major airlines had already started telling passengers to turn off their Note 7s specifically. The second set of devices failed even when powered off.
Here's Time's timeline of events if you want to revisit it. I can understand the first not being caught, but Samsung should have been extra wary of the replacement devices. But no, they only stopped after even more bad news came out.
If Samsung really cared about maintaining quality, they would've taken more than a month to test and ship fixed devices. They should've done a total recall and relaunch a few months later, once they have thoroughly tested their products.
And thanks for the warning about Samsung washers. I have an LG now, and this is the second time the logic board has had an issue in the 10-ish years I've had it (this time it's a sticking relay), and I'm debating repairing vs replacing it. The part is something like $100, but I'm thinking there's a chance something else could die given its age. Then again, $100 is totally reasonable if it lasts another 5 years. If you have any recommendations for brands, I'm all ears.