There does get to be a point where durable merchandise simply isn't worth keeping on the shelves even at mega-discount and is better off in a dumpster. Obviously a lot of this is going to be genuine junk anyway, and as an example, Spencers, known for selling clothing with family-friendly logos like 'Pornstar', are unikely to think the charities will want the remanants of their mercantile screw-up. Obviously the vast majority of crap they yank from the shelves has no genuine value, and it is asking a bit much that they either keep all the stuff even longer - having already decided that they are losing money every moment it stays on the shelves - by storing it for charity perusal. They'll have to devote a lot of time and money to either cherry picking it for decent items or keeping the whole wad somewhere until the charity has a chance to look it over. Destroying crap takes less time, I'd guess. Why they bother to destroy it at all, instead of just tossing it into a dumpster? Hard to say, one might guess that dumpsters known to be full of items some might want will be prone to vandalism. It probably takes less time to destroy a dumpster worth of merchandise then clean up a mess around a dumpster if someone decides to winnow through it, tossing unwanted stuff over the edge the whole while, which could easily result in all sort of hazardous breakage too, like broken glass, and someone has to be paid to clean that up. Padlocking dumpsters is pretty normal, not because companies are greedy or spiteful, but because they know that people or racoons or whatever will go into them and make a big mess. So it's probably not an open and shut case. Most people put solid lids on their garbage cans not because they want to deprive racoons or stray animals of the food there in, but because they don't want to have to clean up a big mess so a stray can get that random turkey bone or moldy piece of bread there in.

If they weren't donating the stuff, then either they just didn't think about it or had decided that even the good PR and possible employee morale boost around doing so wouldn't be worth the total cost, and while I hate to see stuff go to waste and generally feel companies do have a moral obligation to help where they can, I don't expect them to spend a lot of money doing so. Obviously, with media attention drawn to it, the Good-bad PR aspect is much larger, so it may now be profitable for them to change policy, or they may simply not have thought of it.

So I don't think this is really as simple as it first appears to most. I think the first take from most decent people on this is to say 'well, it's their stuff, sure, legally they're good, but it's my wallet and I shop at places that have ethics' which is a fine and fair statement, but the disconnect that worries me is if the media, always happen for a good story, might put an worse spin on it that really is there, since "Large company decides merchandise of little sale value is better off destroyed for following reasons' isn't as catchy as 'Evil company throws away winter clothing instead of donating it to freezing waifs', and just because it is so hard for me to believe they'd do anything that's likely to cause a PR flap for no good reason, I'm inclined to bet there is a second, longer, and more math/economics oriented answer to this which doesn't involve the normally PR/econimic wizards of walmart apparently being blistering idiots and/or wasteful and mean.