The thing to me is this.. if people don't think it's ugly or not.. I'll have to disagree about people buying it for other reasons than the name behind it for the simple reason at any time for the past multiple decades you can type in 'Michael Jackson shirt' on amazon or ebay and buy the same MJ picture printed on a shirt type shirts.. There is nothing new about this clothing aside from branding..
Not really. I just typed in 'Michael Jackson shirt' on eBay, went through the first 10 pages and minus the Supreme shirts/knockoffs that were labelled with said name, there was none of the Billie Jean photo (in fact, there weren't a whole lot in that style of a centred photograph. Some, but not a great deal). It will see more look-a-likes now though simply because of the Supreme collaboration and honestly, if you can afford it, I don't really see an issue with buying a brand's clothing because you like the brand and you like the design.
It's higher end fashion, it's a hobby and when it comes to actual value, it's not about it's literal value so to speak but instead the
perceived value it's assigned by the buyer that gives it the actual value. It's worth whatever people think it's worth. Art is a good example. Physically, art is useless and doesn't really serve a real purpose, but there are art collectors that will drop millions for some pieces. Fashion is very much the same way and considered an art-form by those with an interest in it. Supreme releases very limited quantities and owning a piece is seen by some like owning a piece of art. And of course high fashion is up-marketed, it is meant for a wealthier consumer base. "Not everyone can own a Picasso."
It's not so different from vinyl collectors spending many times the price of a new record to buy an older 1st/2nd pressing of a record they like, sometimes the physical condition of the record is worse too. At a literal value and to non-enthusiasts, you might think a newer, pristine and cheaper pressing to be of better value but the vinyl enthusiasts perceive the 1st pressing to be worth the higher cost. Same for Harry Potter fans who'll spend more to buy a first pressing of
The Philosopher's Stone, etc etc. Or what about audiophiles who might spend an extra $2000 on a sound system that realistically makes little difference to the sound for most people, but they perceive that extra $2000 to be worth it. I'm sure there are examples from many hobbies and ultimately, it's not too different to someone with an interest in higher-end fashion buying a limited-press t-shirt.
Personally I wouldn't spend the prices the resellers are demanding for them. Would I buy the t-shirt brand new? Sure, I like the design, the brand-new price isn't that expensive for a higher-end brand and hey, it's rare which is kinda cool too. Apart from that, I probably wouldn't get any of the items as I don't perceive them to be worth the price charged but other enthusiasts of fashion might like the design, the brand, the fact it is rare and might be able to afford the price just fine. In that case, like the art collector, vinyl enthusiast or audiophile, they perceive the value as being worth it and they'll get it, so hey, good for them.