Full size was retired in 1997, but then brought back in 2014. Check your supermarket checkout lane impulse-buying section. Or you can order them online, though not through amazon for some reason.
I’m guessing it must be a margin or a marketing thing; house-brand baking chocolate products are definitely a thing- for example, you can get kroger-brand chocolate chips, cocoa, syrup, etc… just not chocolate bars. Well, actually you can, but only in the branded “Simple Truth” organic line.
And FWIW, both Aldi and Trader Joe’s are subsidiaries of the Aldi chains in Germany, so their house-brand chocolate presence may be an outgrowth of that.
After all, they are from the land of chocolate.
Hershey’s is the best. If you disagree, you are wrong.
The chocolate industry is a generic market. You buy, you add value, you sell.
Some very small number of chocolate bars are manufactured by growers. Some large amount of chocaolate is retailed by processers. Some large amount of chocolate, including prime, mid-market, and cheap, is bought from processors, blended, made up, packaged and sold.
If you want to sell soft-centres, you buy block chocalate. Even the big companies like Cadburys don’t necessarly do their own processing in all markets.
In Aus, we can get Mars, Cadbury, Nestle, and some of the other big brands, They all have some approximately matching candy bar brands, That is, they’ll have a chocolate caramel bar, a chocolate peanut bar, etc, all approximately interchangable.
Nothing else is like Hershey. Nobody else that I know of uses a recipe like that.
I don’t think there is anything really wrong with Hershey. Yes, it has a 'cheesy" note. Like Cheesecake. Where’s the hate for cheesecake? Yes, it is made with some kind of fermented milk. Where’s the hate for yogurt?
As I noted recently around here, you can really only make s’mores with Hersheys. S’mores aren’t particularly attractive when made with Cadbury choclate. That’s because the cheesecake note contrasts nicely with the chocolate and the marshmallow, otherwise rather sickly sweet. And lots of choclates are made with contrasting notes for that reason. I’m particularly partial to fermented cherries with my top-class chocklate: (cherry liquors).
During holiday shopping season, I have many a time bought a Macy’s Department Store brand chocolate bar, sold at the registers. There’s no food anywhere else, except for boxes of brand holiday candy.
Also, what about the awful $6 chocolate bars our bosses force us to buy from them for Little League or something? Taste like they forgot cocoa or sugar. Generic as hell. 
It’s from the presence of butyric acid. Only their milk chocolate has this distinctive flavor (that some have described as “vomit-like,” and I have picked up on that flavor, even though I enjoy Hershey’s milk chocolate.) The process is a Hershey’s trade secret, but they acidify some portion of the milk, and this process creates butyric acid which gives it that distinctive Hershey’s tang.
I honestly never noticed the flavor until returning home after spending five-and-a-half years abroad. I guess I must not have had any Hershey’s milk chocolate all that time, but after I ate one some time upon returning, I noticed this weird aftertaste in my mouth, as if I had just vomited. Not a strong taste, but definitely a distinct vomit taste. So I googled it, wondering if I was crazy or if something was wrong with my chocolate, and found reams and reams of information and people talking about this flavor, and what causes it (the butyric acid.) Now I understood why non-USAns can have such strong negative opinions of Hershey’s milk chocolate. As for me, I got back used to it and it’s hard for me now to pinpoint that vomitty taste. I don’t notice it. Similarly, when I first had cilantro, it tasted like dish soap, but after acclimating to it, I don’t notice it at all. I mean, I can pick out that soapiness, but it doesn’t register as “dish soap” anymore.
For me the flavor is far worse with Hershey’s chocolate syrup. The chocolate bars are my least favorite chocolate, but I find the syrup to be vile.
I got a plain chocolate ice cream at a local ice cream shop and I immediately tasted that vile Hershey’s syrup flavor and only then did I notice a sign proudly declaring that the chocolate ice cream was made with Hershey’s chocolate.
$6 Little League chocolate bars!? The fundraiser Malley’s bars around here are only a buck each.
And your Little League bars are probably World’s Finest Chocolate, too. Which is the absolute worst chocolate ever (Europeans who complain about Hershey’s have obviously never tried WFC).
Then I think maybe you’re reacting to a different flavor. I have some Hershey’s milk chocolate syrup here, and I don’t taste that vomit flavor – now, like I said, I’m not as keyed into since I’ve reacclimatized myself to Hershey’s chocolate, but I don’t see anything in the ingredients that would contribute that flavor, as the syrup doesn’t use milk, and it’s soured/acidified milk that gives it that taste. Now, I suppose it could be added under “artificial flavors.”
Hey, mister, ain’t no-one gonna be dissing my World’s Finest Chocolate!!! (I grew up and still live within smelling distance of the factory.) I actually do find a lot of their chocolates decent and buy them from time to time at the wholesale outlet they have. I mean, they’re by no means high-end chocolate, but I would suspect the Hershey’s hater would definitely prefer it to Hershey’s, as they don’t have that sour milk taste.
I mean, look at some of these Amazon reviews:
Clearly, a good number of people (myself included) like them just fine. They are nowhere near bottom-of-the-barrel chocolate, unless you’re getting one that has been sitting around in a storeroom for years.