I think the difference in oponions results in what gets the job done and what is great.
Crop sensors, (I've used the XT, 20D, 30D, 40D, and the king of crop sensors, the D300) get the job done. They put out great images in the hands of a great photographer. With that said, they will never be able to have the depth of clarity that a FF sensor has.
As far as the 7D goes, it's a great introduction camera for the professional field. It's pretty much Canon's version of the D300/D300s and goes a long way in terms of the feature list. Will it have the bokeh, color, depth, and iso performance of FF? No. But then, it was never meant to. For all of the great photographers out there that don't have the $$$ to invest in L lenses or 5D2's, the 7D along with EFS lenses like the 17-55IS are a great alternative.
I personally really respect the AF performance reviews of the 7D. An out of focus picture is an out of focus picture, and the brilliance of FF can't change that. Now what Canon needs to do is put the 5D2 and the 7D together and make a D700 =P