As is usual for 5E: Great art.
SWEET! Cursed items right in the normal tables!
If you are rolling random items, it helps keeps the potential results from favoring one particular player.
If one is rolling for random items, it makes sure Consumable magic items still are given out. It also established that consumables are supposed to be a common treasure. For too long players have viewed consumables items as vendor trash to be sold off. Now that's thankfully not an option, it's important to make sure players get enough so they realize they're supposed to USE them.
I like rare potions for the same reason - when you get one you're like, woo! Potion of invisibility... and you save it up for a cool moment to use. If on the other hand you're already carrying 8 different potions, well then you're just using them all the time, and when you find more you're like, yeah, already got that one... etc. Just isnt as fun. I dont want potion use to be common or consistent. I want them to be rare, valuable and unusual one shot magic pills for special moments.I disagree, actually. If you're having random magic items, they should be truly random. IMHO, YMMV, etc.
I think that the item creation feats in 3e showed that, if the cost is low enough, pcs will build it.
Uh... well, speaking as a guy who doesn't have a magic market in my campaign, and who loves a low-magic setting, I like them fine, and I didn't really see how they commoditize magic. But then I saw that you said this a few posts later:
Not sure if you're addressing Scorpio616 specifically or making a general point, but if it's the latter, I again have to disagree. In my 5e game so far, with several pcs having reached as high as 3rd level, they've found about 4 potions, and been given I think 4 more potions of healing by an employer. So that's barely more than 1 potion per pc. I don't want them to use consumables consistently, I want them to have the option to use their consumables when they decide it's worth giving up that item.
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But more to the point: It is because you want the players to acquire enough consumables to use consistently. If you aren't handing them out like candy it isn't going to happen. Every potion that is rolled into a backpack is counting against your preferred style of play.