Oh i know and agree heavily. I bring it up about every time i work on the company forum that we need to have at least one ST50 in store to show customers the differences and benefits. Aside from the better brightness and filter, the ST50 is a better value w/ built-in wifi and additional inputs. Many customers want wifi nowadays and considering we do not sell Panasonics stick in store, they typically walk from the product. We do have a belkin usiversal wifi adapter for tvs but most people prefer first party over third party.
I think they're looking at the fact that the really cheap 720p and entry 1080p plasmas were the ones that sold best, along with the D550 samsung for a 3D plasma. The ST30 nation wide did not sell so hot, although in both stores i worked at we sold them like crazy. We are currently left with huge overstock of 55 st30's nationally (i received 17 of them in early jan, got down to 4, and then received 4 more on shipment). They're probably using the st30 sales figures to predict st50s sales and figure the unit will not be worth it to carry. Better off having something similar to the D550, which is why we have the UT50. Im carrying half the number of plasmas as i did last year, which is a real bummer.
The above is only a guess as to why we are doing what we did, but that's the type of response i got when we dropped 1080p 42" plasmas last year because the 42" S2 was not a hot seller. We'll still be carrying higher end LEDs, aside from stuff offered in MHT (though very few select stores will get real high end stuff like the 84" LG LED).
EDIT: Looks like i was correct with my assumption above. Here's what AVJunkie said at HDJ, "sears doesn't carry st50 in store. Cause they couldn't even sell st30 well as a whole. Most likely ut50 as its the only pdp they were sent.. Again why he said 55 st series for $1000 .. Seems he maybe a little confused "