As long as they don't take the information and sell it to other companies, there is no real problem with this. The government doesn't care that you watch ridiculous amounts of internet porn or cheat on your wife. They are looking for potential information on illegal acts and really couldn't give two flying fladoodles what you are doing as long as you have nothing to hide legally.
While I don't believe that government should have free reign to snoop on random citizens cell phones whenever and wherever they feel like it, I do believe that monitoring certain individuals phones could be incredibly important in certain situations. As long as it's a matter of safety for innocent civilians and certain variables are present, I think it may be necessary.
Ever since the revelations revealed by Edward Snowden, there has been a tremendous amount of public uproar over the so-called violations of privacy. But to that I can only respond that these people are simply naive if they have not realized that the government has been doing these kinds of things regularly for decades, and indeed, that the great social stability we have experienced is in large part owing to these measures.
Your smartphone is your private device. Tracking phone calls / texts made from it is different because that goes through a cell tower not your phone -- I think it still should not be done unless a certain person is suspected of terrorism and then only that person's calls are monitored, but you get the idea, it's different. But going through your photos, videos, etc. SEARCHING for evidence is not good. It is a violation of the U.S. 4th amendment. It was established in 1967 that phone calls are constitutionally protected from wiretaps without a warrant, but still because of the Patriot Act (2001) the government gets to do it anyway... The government today is just broken
While it it easy, in this trying times, to let fear get the better of us, we must not sacrifice our basic rights for the illusion of security. The right to free association and the right to privacy, are recognized by the UN as a basic human right. The government insisting upon the need to spy on people's phones, is little more than treating the populace as criminals without even the most basic of trials to prove that the people are a threat.
Smartphones should only be looked at if there is a warrant issued and a person is suspect of wrongdoing. The government can't just go randomly searching on people's smartphones. That is invasion of privacy. They would have to have some good reason to attempt doing that, not just because they could.