Sandy Bridge-EP Xeons are cheap because they're next to useless. Some enthusiasts used to pickup old Xeons and overclock the crap out of them long after they were retired, but many bought Xeons instead when they were new over an i7 due to their superior binning.
All I want is the top bin Xeon SKU to be unlocked, not all Xeons. Unlocking only the very top SKU would harm exactly nothing as their volume as compared to all Xeons is quite small. If someone wants to spend $4.5k on a CPU and a small change like an unlock makes that CPU far more attractive to them, is that not preferable than only offering them a $1k CPU?
Intel is beginning to see that some people want more (and in some cases far more) than the top HEDT CPU offers...and are willing to pay dearly for it. This is why this new 10-core is being trialled at the $1500 price point. Substantial enough sales of these niche products at higher price points will make them consider higher core counts in the future, for a price, of course. The reason why we don't have $1500 processors already is due to the failed QX9775 experiment where Intel tried to market a premium product at that price point once before. They failed because enthusiasts aren't stupid...they took the cheap, low speed Xeons available and overclocked the crap out of them on the D5400XS. D5400XS sales were good from what I read....QX9775 sales.....less so.
This time of course a premium product is being offered with no real cheap alternative (like an overclockable and cheap LGA771 Xeon) being around. The unlocked 10-core will sell very well...and Intel will be quite surprised at this. They may then consider offering more higher core count unlocked chips in the future at higher price points. If they decide to do this, the chips may stay branded as i7s or become a unique brand like Xeon Extreme Edition or something similar to better justify a top echelon price, but still keeps them distinct from the mainstream Xeons.
I hope and pray such chips come to pass...