What you say is true. The Catch 22 is after about 1/3 tread wear, the soft compound is gone and you're left with a regular tire. There are TONS of used sets of Blizzaks for sale on CL and I suspect that when folks realize the advantage is gone, they're left with a very ordinary tire ! CraigBut the Blizzak rides so smooth and silent in the warm weather.
I put my Blizzaks on last winter and kept them on because I didn't want to shell out the dough for new rims, air pressure thingamajigs, etc.
I know a couple others in my area that do the same.
I drive maybe 9000 miles in a busy year, generally around 8k so I'll still get good mileage out of the tires before they need replacing.