I understand your point. From a legal point of view there is no difficulty. I would, however, suggest that there is another way to look at it as well.
Can you ignore the reality that people will tick tick boxes without knowing what they are agreeing to? Ask some Facebook users what they think the user agreement looks like, or what it might mean to them. I honestly don't think that many people are very cognisant of what they are agreeing to on-line. This is a similar situation to getting consent from children who are under age - they don't understand the ramifications and hence are incapable of giving consent. When it comes to on-line activity,I think many people are co-opted by social pressures into agreeing to documents which they have not read and may in fact be unable to understand. Is that really consent?