Originally Posted by wizard69
In the end there are two values this offers the user. One is flexibility to use the screen you want matched to the CPU you need or in a word flexibility. The second value is in far easier maintenance and an easier approach to obsolescence.
Because it would allow Apple to make a far greater number of customers happy without really giving up much at all. The more flexible approach means that systems end up tailored to the users need. In this case they would actually be able to trim the actual number of desktop products offered.
A big thing for the consummer is that it does away with some of Aples stupid marketing tricks. For example any Base Unit could be fitted to any monitor. Thus you don't have to settle for lower performance because you don't want the largest machine.
This is where I think you're not understanding how Apple works: Apple does not care about this thing you are calling 'lack of flexibility', and does not see it as a problem. If they did, they would have changed the line five years ago to entice more switchers. They didn't, and the switchers came anyway.
Right now, ~70% of Apple's sales are laptops, and the increasing power of the MacBook Pro line is only going to increase this number. So, going forward, 70%+ of all hardware sales are already eligible for your scenario, regardless of what Apple does with the desktop. Those customers may or may not buy a larger monitor - Apple's Cinema Display is clearly designed for laptop use, since the cables aren't long enough to reach a Mac Pro under a desk. Regardless, Apple makes a pretty hefty profit on the MacBook Pro, so they're happy either way.
The mini exists for switchers, co-locators/people who need a small server, and those who already have a monitor that they want to keep using, either because it's a good monitor, because they can't afford to buy a new one, or they don't care that much about monitor quality (like my sister, for instance). Apple has an iMac that's much, much
better than the mini, in every way, for $500 more, and that includes a very nice 21.5" monitor, so if you need a monitor and can afford $500, you'll see that as a very good deal and go with it.
If you're a switcher and you buy a mini, within two years you will probably buy an iMac (because your existing monitor is starting to feel old and small) or a MacBook Pro (because you decide you want to be mobile). Either way, they eventually move you to a solution on which Apple makes more profit, and cuts out other manufacturers. Co-locators don't care about monitors, and people who still can't afford/don't care about a new monitor will buy another mini (again, like my sister).
If Apple changes the line as you describe, all desktop buyers will be free to mix and match as they like. This would be a problem for Apple, as they'd really like you to buy their monitor, but there's nothing that will force you to do so - all you need is something you can attach a Thunderbolt/mini-displayport cable or adapter to, and that covers just about every monitor on the market. With the current iMac design, Apple offers a very cost-effective solution that takes up less desk space than a monitor+CPU setup, and which (coincidentally) makes Apple more money than if you were to buy a similar 'headless' Apple CPU and a monitor from somebody else.
There's just no reason for Apple to move in this direction - they make more money via the iMac without ever facing the risk that someone will buy the Xmac CPU, then run over to Best Buy for a Samsung/LG/HP/whatever monitor to use with it. If you need more power than an iMac (a smaller and smaller part of the market, given the power of the quad-cores), they have an extremely expensive Mac Pro that they'd be happy to sell you, and makes them enough money that they don't care so much that you'll probably buy monitors from somebody else.
This lack of flexibility that you describe is a genuine problem, to the point of not purchasing a Mac, for a very, very small number of potential customers. In the end, Apple will just content themselves with selling these customers an iPhone and/or iPad, and will not lose any sleep over it.