Agreed, the images do seem lower quality than they used to be.
I was curious, though, and chose buildings at random around the Google office in NYC, just to do a side-by-side, and even the old pictures look better:
I'm assuming left is old and right is new? This looks like aerial photography shot from a plane rather than satellite imagery, which seems like it would depend more on the quality(?) of the plane than the quality of the cameras.
