I'd say that very much depends on why you believe the warrant process exists in the first place. I honestly don't know that much about the historical context of search warrants. Do they exist because philosophers of old believed in a right to privacy as an end unto itself? Or do they exist for some more practical reason, like because they were used for extra legal retaliation against enemies of the state, or for intimidation, or to go on fishing expeditions.

Or, why does the protection from self-incrimination exist? Is it because we are concerned that the government might have access to your thoughts? Or is it because the government would torture people to get confessions, and the people wanted to remove the incentive to do so?

Depending on your belief about this, you might feel differently about what should be done about this Google situation. If you believe the latter view in the second paragraph, for example, you might have no problem with the breadth of the search. In fact, you might not even have a problem with involuntary brain scans, provided they were proven accurate. As long as the rule of law is strong and the materials were used only for a defined and limited purpose, you might think it would be better if the government could compel the true personal perspective of the accused.

So this really enters into questions about each individual's perspective on the purpose and value of privacy. I think it might not be accurate to say that people who say it is justified are missing the point. They might just think the point is different from what you think it is.