Has anyone thought that Subaru is trying to cover their own ass by putting that type of 'requirement' in the manual? There are different types of things that break windshields; a tiny pebble chip to a meteor falling at MACH speed through the windshield and into the front seat. I would say that the latter would require re-calibration.
2 years ago I got a stone chip (not along the defroster area) on the passenger side that eventually cracked to the middle of the windshield, about 4" from the bottom. Eyesight didn't freak out while it was cracked, but I knew the car wouldn't pass inspection with it like that. I called the local dealer, they gave me a list of suggested local companies that would replace it with "OEM" glass. Long story short, the company replaced the windshield in the parking lot at work. No calibration needed and Eyesight works perfectly fine - adaptive cruise, object warning, lane warning etc.
My point is, if a meteor hits your windshield and hoses up everything, then it's a no-brainer to get ES calibrated. If it's simply sliding out the old cracked windshield and sliding a new one in, I don't see the point in re-calibration.
PS - it's a huge PITA to get a windshield replaced in Pennsylvania using insurance.