Designers can only aim to produce work that challenges "constraints, organisational politics" if the client will allow them to. Very few will. You can explain until you're blue in the face that they're shooting themselves in the foot, but in any organization the easiest and safest thing to do career-wise is to avoid rocking the boat, so very few clients are willing to push back on all the different internal pressures that hobble their projects. It's easier to just accept them and deliver the best thing their internal dysfunctions will allow.
(This is as true for consulting coders as it is for consulting designers, btw. Even the original consultant, Sherlock Holmes: Consulting Detective, could never get the London police to take his word for things.)
And it's easier for designers to go along with that too than it is to refuse to work for clients who insist on shooting themselves in the foot. But it's hard to blame them. Designers gotta eat too, you know? I mean, you can play Howard Roark and refuse to work on anything that's in any way compromised, but since reality isn't a bad novel you may find yourself going your whole life without ever finding a client who meets your standards. And is a brilliant designer who never got around to designing anything really better in the final analysis than a brilliant designer who designed a bunch of nearly-great-but-sadly-compromised things? I dunno.
You can't represent the customer without doing some real research with real customers. I can't remember ever seeing those sorts of results in a spec redesign post.
Instead, I think they are using the brand as a canvas to show off their own abilities. And they always pick a big popular brand, because then they can leverage that popularity to promote their work.
Teensy bit bland for my tastes but it goes to show there are designer out there who do some quality redesigns.
First, most of these redesigns are done in good fun, as a thought exercise for the designer. New thinking applied to familiar context.
But secondly, it's so important to understand that all brands and interfaces are ultimately judged by your customers, who have "no knowledge of [or patience for] the requirements, constraints, organisational politics." I've just heard that argument way too often used to prop up a poor design outcome. Good design remembers that the context of your product is in the hands of your consumer, not in the conference room of your headquarters.
If someone outside your company offers some free thoughts on your brand and identity, it's not a bad idea to look them over. They are relating to you as a customer. (And usually, a huge promoter.)