The photography of an individual can constitute harassment even in a public place - there is no implied consent involved. Even if it were, as you implied, perfectly legal in all cases then this in no way makes the act ethical. This is especially true when concerning a new technology which makes it trivially easy to perform. I'd expect if Glass, or some descendant of it, becomes more ubiquitous, then social guideline and laws would eventually prohibit it's use in certain situations. Would you, for example, be happy with someone recording you in a public restroom?
You're also repeatedly missing the argument I've already made twice in this thread with your second paragraph,
Filming someone is rude. What are you going to do about it? Ban smartphones? It's trivially easy to pretend to use your phone while secretly recording. Ban DSLRs? I could pretend to be taking static pictures while actually running a video. Ban video cameras? They might look like they're idle, but maybe they're recording with the "recording" light turned off. Ban surveillance cameras? Hell, anyone can hang one of them on a building, and who knows where the video will end up?
I'm not missing the argument. You're just not making an argument worth refuting. "Oh no, someone has a device capable of recording me" so fucking what? Welcome to 1975, you can buy recording devices at a dollar store. No one looks twice when there's a CCTV camera or a smartphone out in public.
You hate Glass because it's unusual, not because it's capable of recording you.
You're also repeatedly missing the argument I've already made twice in this thread with your second paragraph,