Moving militaries to replace police on some institutions' security is and was stupid, as it's not their core mission. But calling "citizens street protests" the guerilla-like behaviours that triggered this clumsy response from the government is a bit naive and misleading as well.
If you study France's Fifth Republic rules (Constitution), you'll see the president has some discretionary power that are not democratic, in order to be able to take on decisions to safeguard the republic - that's a direct heritage of De Gaulle, that saw that in 1940, the president had not the power, and could not decide to make the army react fast enough to counter German invasion.
So, nothing real new so far.
This initiative was supported by Macron, as it was by many others. Nothing new either that France (and French cultural crowd) has always been historically in favour of this kind of copyright move, or even stronger ones.
I'd say that the republic was not put in danger by these protests and that this kind of move creates a very dangerous precedent. I also had thought that "La Révolution française est terminée", to quote Francois Furet, and that's why I think that "de facto" no-one was expecting any French president to send the troops. Did De Gaulle send the troops in May '68?
On the rest, we differ. I'd say that these events are very, very concerning - especially given that the team in charge of the country is clearly not as experienced/diligent as the previous ones, yet.
However he's completely in his right to have the army against disorderly protests that cause damage (including fire to historical buildings the last time).
What's worst is that the crooks that run things around my part of the continent (I live in Eastern Europe) have given Macron's recent actions as an example, as in: "if France's rulers are happy to tear-gas their own citizenry why are we blamed for doing the same thing"?
Now, a state (democratic or not) _has to_ show force, because that's one of the definitions of a state: an entity that takes the monopoly on violence.
Given the violence that demonstrated itself in some very specific places by very specific groups of people (and disrupted things even worse for others), it has to be expected that the state reacts. The contrary would be a sign of weakness through which more chaos would pour.