The French police live in French cities also, and they have families and friends who could fall victim to terrorists attacks. They are not going to standby and let terrorist attacks happen if they have the knowledge and power to stop them. The trouble is, even if they knew, they still would not be able to stop it. Except for an extreme circumstance where an individual has credible information and is being ignored, no French civilian and certainly no non-French person who knows nothing apart from what is filtered through foreign media before being released through domestic media has any justifiable reason to claim the French are not doing the best they can with the information they have.
People need to realize that it's not cut and dried. You can't just stop terror attacks because you want to. They are almost impossible to detect. If you go to far you are stepping upon the liberties that people expect government to preserve. It's a fine line that must be walked.
After the recent terrorist attacks in Paris and a foiled attack in Orleans region, France has stepped up their police efforts to protect their citizens. Excessive police presence does not really guarantee safety but only works to make the situations more uncomfortable for citizens. Fear mongering should not sway people to believe they are not safe.
I don't think the French police are doing enough to protect their citizens. For a very long time, the French were very open as to who they allowed in the country. I think that is quickly proving to be a problem. I think you're going to see more and more threats similar to what was seen in the Orleans region.