Because there isn't such a thing.
Or am I missing the universal 'connect devices to stuff' dock? Or maybe you mean a 3.5mm jack plug (for audio), which many cars/stereos support.
Or bluetooth for the phone?
I'll agree that a universal standard for this kind of thing would be a good idea, but there isn't one. USB comes close, but then again my phone has a proprietary connector on it so I have to use a special lead..... (nokia)
Mind you, I think you're confusing 'devices that work with the ipod' with 'devices'. My recently bought clock radio doesn't have a dock connector, and even a cursory glance through Amazon will show that the devices fitted with ipod docks make up a relatively small section of the market, so manufacturers are hardly /forced/ to adopt it. (Many things simply have USB connections for example.) There is also more than one type of dock connector.
What vicious circle is this anyway? The vicious circle that was caused by Apple releasing an expensive media player into a crowded market that was so poor and did so little of what people wanted from a PMP so badly that it took a good percentage of the market? I've said it before, if you don't like it don't buy apple, there are many many other choices.
The grip Microsoft exerted (as they seem forever to be compared to each other despite being quite different arguments) was an almost total control over the desktop OS market, which they were poised to use to increase this to an almost total control of your pc (Office suite or nothing.) and was demonstrably harming innovation in the PC market.
"If you have even a sneaking regard for the value of Open Standards, and their power to make things better for everyone, this should concern you."
I don't understand 'make things better for everyone', by most accounts the iPod is one of the best media players out there, and the iPhone was released with a lack of many features considered by most to be important (MMS, 3G) and yet offered a good enough user experience that people paid a premium for them in their millions, which would suggest that maybe it is in some way better. (Looking at how it's become the 'device to beat' even though it only has a <5% market share should tell you something here.)
Or do you mean on some more idealistic level? In that case I'm not quite sure criticising a consumer electronics company is entirely productive what with all that starvation and death in the world.
Assuming you do mean in the IT field, what about the other things they do, for example the grand central dispatcher stuff, which is a fairly decent stab at addressing the problem of writing highly concurrent apps that best utilise multiple CPUs, as I understand it their implementation is open source, and the language extensions they propose have been submitted back to the relavent standards bodies? Doesn't that sound like they're trying to 'make things better for everyone'.
Or the mini display port connector they invented?
At the end of they day though, they are a big evil corporation (by definition, most big companies are), but they aren't (yet) a monopolist.