I know more about France than you do. Adding 'in my opinion' to the end of everything is pointless, it's fairly obvious it's my opinion.
I was merely pointing out it was a pity that the gunman couldn't have been caught alive, I wasn't criticising the Fench police for not doing so, because it was fairly obvious he wanted to go out with all guns blazing.
If one does not add, "in my opinion" then a reader might believe that the poster is claiming that his/her opinion is objective fact.
And, in your second paragraph above, you cannot claim it is a "pity." One cannot ascribe an emotion to an event. Many people emote differently. Emotions are always subjective.
One can only claim that in one's opinion it is a pity. Also, nothing is "fairly obvious," unless one was involved in all communications during the standoff.
If one posts in colloquial speech, then one might not be making a cogent argument, other than an appeal to emotions that are popular for a situation.
It is very elementary Watson.