As much as I truly love replaceable cords, I'd be more than happy enough if I could just unscrew the shell of the device, unscrew the power wires from where they attach, and put in any cord. Where I care about waterproofing, some silicone caulk is an extremely cheap (and removable) fix.

Unfortunately practically everything you can buy now is welded plastic halves, or easily-broken clips. So even when you might be able to do this internally, you have a high chance of breaking the shell even if you know what you're doing.

The one integrated cord that bugs me is the one in my 1987 vintage ADA MP-1 rackmount guitar pre-amp. Every time you take thing out of the rack to do something with it, like diddle around the circuit board, there is always that cord dangling out of it and getting in the way. The connections have become flaky somewhere as well.

I keep telling myself one of these days I will convert it to a C13 connector. Or C5, it that would fit better.

One very practical reason that comes to mind is waterproofing. Kitchen counters get wet, and office desks do not. Anything with a plug is at greater risk of shorting.

This is my pet peeve about USB-C laptop docks. The vast majority of them have a captive cable, usually about 10cm long. It's a failure point, often an inconvenient length, and makes them much harder to pack.

Headphones are a big one for me. By their nature, the cords are often going to get snagged and tugged on and are pretty much guaranteed to fail before the headset itself does. I'm pretty happy my current Sennheiser headphones have detachable headphone cables, though the shaky ground the company itself is on makes me wonder if I should stock up on a few...

That's one of the reasons I love Festool's tools, nearly all of them have detachable power cords. It's a proprietary connector, but it makes it very convenient if you own a few of their tools. Both the power and dust hose have twist lock connectors that stay firmly attached in use.

I’m a big fan of this notion. My hot water dispenser has a magnetic power dongle kinda like macbooks MagSafe, but bulkier [0]. Ideally something like that would be more standardized across appliances the way some of the other three prong power cords are.

[0]: https://youtu.be/E2WrHHRYrV4?t=108

Regulations make detachable cords of electric kitchen appliances hard.

Most need double isolation and water-proofing, hence not detachable.

It could probably be done, but it likely needs a different type of connector, akin to M12/M8

Because the cord is rated for the appliance. It is a fire thing. Let customers swap out cords and one of them will use an underrated cord and cause a fire. Or they will use a cord without a ground.

Ironically, Christmas lights make great (ie safe) extension cords because code mandates they have biult-in fuses, unlike any other cord which is just wires without any overcurrent protection.

The plug between the cord and the device must be sturdy and meet regulatory standards

So it is expensive

It is cheaper to just attach the cord

That is the reason

Erm, let's not.

Take one look at the mess of incompatible detachable cords that come with LED lighting fixtures from China to see what results.

They could have used bog standard IEC 320-C5 cables, but they didn't. Why? Because they wanted to cheap out on the conductor AWG and IEC 320-C5 is quite specific about the conductor gauges and current capacities.

So, the LED lighting manufacturers produced a bunch of cables that are in almost exactly the same shape and size factor as IEC 320-C5 while being just enough incompatible to not invoke the certifying authorities--all to save a couple pennies in copper.