It was inevitable. As soon as someone said, "Bra," there were guys who would have a really negative reaction to the original equipment case.
Is that original case quirky? You betcha. A very interesting series of design decisions, including keeping the weight and bulk down by protecting only the ear cups and turning the headband into the carry handle. It's not conventional, so naturally, there are those who want something more typical.
All headphones at that price point have to come with a case. You think Apple's getting grief over the design of the case? Just imagine the noise if there had been no case at all. About the only thing I haven't read (yet) is, "Would Jony have approved those?"
Would I pay $100 to replace the original case? No, because my lifestyle these days is very sedentary. The cans would spend 99.99% of their time in my bedroom - no case required. If I was flying regularly (as I used to), or if I was still recording concerts on location and these turned out to be suitable to the purpose? I suspect I'd stick with the original case. It doesn't offend me enough to want to spend money on an alternative and like those weird-looking original AirPods that nobody would ever be caught dead wearing... there's something seductive about using an Apple product that shouts its identity to the world.
Do I care for this particular Waterfield case? Not really. I think its aesthetic is at odds with the design of the object it encloses, but different strokes for different folks, right?
Now, what about foldability? Apple made certain decisions about the fit and design of the headphones. Might they have gone with a foldable design? Yes, but as someone who had a professional relationship with studio headphones for over 25 years... I suspect what Apple came up with will turn out to be far more durable/reliable. Getting a good, tight ear cup seal isn't as easy as it seems, and in my experience the cans that sealed best were not particularly flexible - they depended more upon a tight, springy headband and a mechanical connection to the ear cups that had a minimum of "give."
The professional cans I used did not fold like those ATs, which have a design heritage going back to the Kudelski and Beyderdynamic headphones favored by the guys with the Nagras (film sound). Before AT, Sony had popular models of similar design (hey, video guys need cans, too). They looked cool, sounded fine, but they didn't deliver the kind of isolation I preferred when mixing music in the field. Foldability isn't as important as functionality.