The focus of the comments is not the disjoint between software and hardware releases, but rather that manufacturers are very slow to update to newer software releases. That's what everyone's complaining about. Sony Ericsson releasing a new phone with an old operating system is just another indication of that.
For your comparison to be accurate, Apple would have had to release a new Mac that didn't run Mountain Lion, two months after Mountain Lion was released.
Or, HP would have had to release a new laptop that didn't run Windows 7 after Windows 7 was released. There's nothing wrong with doing that, but it's unlikely to happen simply because Microsoft is providing HP with prereleases way before a new Windows version is announced, while Google is currently only providing that service to their Nexus launch partner (at least that's the excuse that Sony Ericsson had).
Other people not doing it doesn't mean there's anything wrong with it (as you yourself have pointed out twice) so... what makes it bad?
Google lets consumers use products that it labels as "beta"? Is this bad? Why?
Google only let people with invites into Gmail at first. Is this bad? Why
Google tests changes by pushing them to random subsets of web visitors. Is this bad? Why?
Google pushed the last version of the market to 2.3 devices before it pushed it to 2.2 devices. Is this bad? Why?
Android updates seem to roll out by country over a period of weeks. Is this bad? Why?
A lot of Android functionality is in Apps rather than the OS and the trend is to increase this (e.g. Chrome on a 6 week update schedule). Is this bad? Why?
You could have interesting, enlightening debates about any of these decisions and reasonable people could argue either side of each of them. But it seems we skipped that step for Android updates and decided that if it wasn't the same as Apple it must be bad. I'm just looking for an actual reason why an average consumer (or indeed any particular subset of consumers) would prefer everyone to adopt Apple's model to justify these strongly and loudly held opinions.
Note that "not having the latest version of the OS" is not a reason why not having the latest version of the OS is bad, it's just restating the question.
This is not really about "Android vs Apple" or Apple fanboys trying to push a certain view on others. What it's about is carriers and cell phone manufacturers being used to shipping phones with a single OS release, and never having to provide any updates at all (except for serious bugs).
The only thing special about Apples software update policy is that it's more similar to how things are done in the PC industry, where you get OS updates as long as your hardware supports the new operating systems (although Apple is quicker in discontinuing iOS devices, something I don't like).
I can't think of a single reason why delaying, or not shipping a software release for a capable (but discontinued) handset is _good_ for the customer. I can think of many examples of why it is bad.
If your theory is right and a year from now I'll be able to upgrade an Android 4.x phone to be feature equivalent with Android 5 through app downloads, then great, why would anyone really complain about that?
An example of the PC and mobile worlds colliding: When Nokia discontinued the 770 with the Tablet OS 2007 release, do you think the outraged 770 owners were rabid Apple fanboys? No, they were PC users that expected the expensive toy they just bought to be supported for more than a year and two months with software updates.
For your comparison to be accurate, Apple would have had to release a new Mac that didn't run Mountain Lion, two months after Mountain Lion was released.
Or, HP would have had to release a new laptop that didn't run Windows 7 after Windows 7 was released. There's nothing wrong with doing that, but it's unlikely to happen simply because Microsoft is providing HP with prereleases way before a new Windows version is announced, while Google is currently only providing that service to their Nexus launch partner (at least that's the excuse that Sony Ericsson had).