Chiming in to say I 100% agree. People use the URL as a 'gut check' to ensure they are not on some scam/spam site, and AMP screws that up.

I'd be very interested to see numbers on the success rates of lookalike phishing sites once people get used to AMP and stop checking URLs to see if they're in a valid location. I wonder if you could somehow track this with google trends over the next year or so?