Fair enough. Nevertheless, a company like Google could certainly afford to be gracious with developers and let them contribute to the future product's success without making them pay a hefty amount.
There still has to be a barrier to entry, or everybody and their mother would apply, and just leave the glasses sitting around on the table when they got bored with them. The price tag will weed out all but those serious about developing for glass and few peeps with disposable incomes.
Think this in Google's perspective. If developers are begging to take their money, why would they refuse?
I think it's more likely they want to filter for people that are serious about it.