It does seem to make sense to me that Google would partner with a company that can place Google Glass in front of the average consumer. Luxotica owns 7000 retail locations [1] and I am pretty sure most of those locations accept EyeMed insurance (which Luxotica also owns). People would be very happy to put their insurance benefit towards a pair of Google Glasses.
I'm on my second pair of WB frames because I don't like spending a ton on eye-wear. I understand the value that WB provides to consumers. I just think Luxotica currently offers way more to Google than WB could.