Why do newer imacs have slower processors?

Ok so just read this "Somewhat unusually, rather than "refresh" the entire iMac line with an across the board upgrade of all models, Apple decided to release a new lower-end, cheaper entry-level "Mid-2014" iMac -- the iMac "Core i5" 1.4 21.5-Inch (Mid-2014) -- and sell it alongside the previously introduced "Late 2013" iMac models."

Which makes more sense now and what Malcolm said earlier. It's a cheaper version and actually only duel core. Don't know how I misread it ion the specs page. I haven't looked at the later ones yet so I'll take a look at them.

what would be a good judge then? clock speeds are how fast a computer can process information pretty sure that's a pretty good standard. Clock speeds are everything when rendering images and those apps like Autodesk Maya and Pixar's Renderman use the full capacity of the CPU. So knowing which is faster is kind of important. I get the feeling that the older version is faster at this point. The CPU's are called the exact same in the apple descriptions except the older version has higher GHz so apple is ripping people off with the newer one. And to top things off the older one has 1TB hard drive compared to 500GB in the newer one.

Again I don't see how that is the case? I am reading the specs and 1.4Ghz is 1.4Ghz not faster not slower. I don't understand. I come from PC (windows) and have bought and installed replacement parts for my PC. I would not choose a 1.4GHz quad core over a 2.7Ghz quad core if I were looking for a better PC.

so If I were buying a used imac then getting an older version would be better than?