I find that MR is a pretty good judge. Look at the buyer's guide - they say don't buy, updates are coming, and the reliable sources put it at august. The OP should be excited, as this creates an opportunity in a few weeks
There's been issues with it before (try searching MR's MP threads). Taking the particulars into consideration, they can't build systems with vapor, which will extend the days of an update cycle (should be common sense - if the parts take 500 days to begin shipping, then new systems can't show up before the parts do). They need CPU's that are viable for a new model Identifier in order to keep improving performance. Of what's been announced by Intel, the LGA2011 is the only possibility that would fit such a requirement.
Look at it this way... why would anyone in their right mind buy a new system that's at best a couple of percent faster, and likely pay a noticeable amount of additional funds for it (TB alone will push the production cost, and margins will be on top of that). Particularly when there's another new system due out in 6 months?
And you've apparently no concept of the financial implications if Apple attempted this (or any other vendor for an enterprise grade machine).
The devices, laptops, Mini and iMac are consumer products, not enterprise products (workstations and servers are). So the rules that govern this particular market are quite different from those on the consumer side (i.e. gimmicks can be used to sell consumer systems marketed as a new model, even if all that changed was a peripheral component). But this won't fly in the enterprise world (too expensive, and those that buy them use things like cost/benefit analysis to see if it's a viable path or not).
In other works, decisions are based on math, science, and logic, not emotion ("I just gotta have that new toy!" logic that applies to consumer products - it's technically called an Impulse Buy; but those that buy for professional use have to temper this, as their jobs are on the line if they screw up, and can even cause a company to go out of business - taking others' jobs with it, so it's not just how the individual is affected by a bad decision).
