No, I don't. My current setup requires several power bricks ("weird boxes") for the displays and speakers anyway. The good thing about those is that you can just hide them away, unlike your monitor. And what exactly is the problem with extension cords?
The nice thing about the All-In-One Macs was always how portable they were. The Mac Plus, the Colour Classic, the all-in-one Quadras, and every previous version of the iMac -- just a single box, a standard power cable, a keyboard and a mouse.
It was always a lot easier to move them around than the PC towers everyone else had. Apple even ran an ad once that showed how few cables iMacs had in contrast to a typical PC.
I mean, it's not a huge difference in portability, but it's an Apple product -- people obsess over details like this, and they pay a premium for a product that gets it right.
Also, it's nice that you can hide the external PSU in your setup, but often that's not easily possible. Eg. if you have a minimal setup with a sleek desk, there's just no place to hide the power brick. Or if you bring the computer to the living room to watch a movie... I mean, there's lots of ways to use this computer, and the external PSU is just optimized for one use case.
And it's made even worse by the fact that many people are going to end up having to attach an external hub with an extra power brick since this iMac severly lacks ports.
EDIT: And you can see that Apple doesn't like the PSU since it is conspicuously absent from their marketing page. Even the "What's in the box" picture hides the PSU: https://www.apple.com/shop/buy-mac/imac
They know that (some) people don't like power bricks.
There are desks that solve the cable management issue by mounting a tray just underneath the tabletop. If it's such a problem for you, a desk like this is probably worth it.
The portability argument I understand though. I regularly move my desktop between two places and having duplicate cables and peripherals for each one has been very convenient. So seeing that, you're actually right, I would need to either buy a probably fairly expensive proprietary cable or always carry the brick; and an integrated PSU would've been more convenient.
But in the end whether this tradeoff is worth it comes down to your particular situation, and apparently Apple have decided that in general it is worth it. Personally I also don't think too many people move their desktops around that much.
The point about the power brick not showing up on the page I'd chalk up to OCD design, not malice, to be honest. It is at least hinted at because the two pictured cables are different.
