I didn't know there were issues in particular with Storm Lake, but the other brands are not known for their quality reputation. About the only thing good from Tapco are their AK trigger sets and the AK hammer and trigger pin retainer plate that replaces the wire shepherd's crook. I'll probably buy a couple of the plates before they are gone from the store. Though I have no doubts someone else will pick up the slack.
Bushmaster is pretty much poison. They've got a big bullseye on their backs because Bushmaster rifles were used in a number of "mass" shootings. So I expect part of the decision is damage control. If you want Bushmaster clone, Wyndham Weaponry started up making the same guns, with the same quality, in the same location, after Remington purchased the name and started making them in NY. Bushmaster and DPMS have also been facing competition from companies making better guns at lower prices. Tough to stay in business.
My bottom line conclusion? Remington leadership decided that the political winds are blowing the wrong way and they are better served by distancing themselves. You could defend their decision as not taking a political stance, just an economical one. However, I'm not going to defend them. They need to get their house in order on their core guns that have had quality control problems for awhile.