I think that this is kinda a standard French security theater thing, as France has done it repeatedly before. Some terrorist kills some people in France, French government deploys a bunch of soldiers to visibly stand around in public places, public is satisfied that something is being done.
The real stuff that France is doing to deal with terrorism is going to be on the intelligence side. Can't really see that, though, so to the public, looks like the government is just standing around doing nothing, which I imagine is annoying to the government.