Google is working on integration with prescription glasses. They have dark-glasses versions. The display only takes up a little bit of your field of view so I don't see a problem as currently designed for most situations. Re. texting, the display isn't terribly practical for reading much; Google wants you to operate Glass with your voice and have texts read to you, I believe. I still think 90% of driver distraction problems of electronics is operating the gizmo at all rather than operating it with your hands, so I think Glass is potentially an incremental worsening of the situation. Fortunately, we'll all be spacing out in Google self-driving cars so it won't matter.
I agree people wear glasses a lot, but I don't think Google is trying to capitalize on that per se; it more boils down to where else are you going to put it? I do think it's different with the little camera peering at you, and if people's attention wanders to the display, you'll notice it just like you notice when the person you're talking to checks the mobile phone mid-conversation. None of these are insurmountable, but I think there will be adjustments required.
Your mobile phone is more convenient, and you can put it away, which I think is a feature, not a bug, at least in many human-interaction situations. You can't take videos and photos using your phone unless you have hands free, though. Driving directions will be wherever you set your phone down, not hovering up above your field of vision. There are a lot of compelling advantages to Project Glass IMO. I wouldn't be surprised if it ends up being more an adjunct to your phone than a standalone device, though.