But let's not forget that back in the 60s the French public at large did not take all that much interest in the likes of Godard, Truffaut or Chabrol and were a lot more eager to line up in front of theaters in order to watch spoof film noir offerings like "Les Tontons Flingueurs" or traditional comedies such as "La Grande Vadrouille".
"C'est pas parce qu'on a rien à dire..." was released in 1975 and marks the transition between the older generation with household names such as Bernard Blier and Jean Lefèvre playing the main parts while the upcoming generation here represented by Jugnot and Lhermitte only briefly appear but would soon become favorites of the French public in their own right.
Interestingly, another protagonist of note in this movie, the "Dame Pipi" who is in charge of the public bathroom where most of the action takes place, is played by Tsilla Chelton (of "Tatie Danielle" fame) who taught an acting class at the time, and the Troupe du Splendid were among her students.
As to the movie per se, do not expect anything memorable, but the dialogs are consistently funny... (trust Blier, Lefèvre, and Serrault of course to deliver them in a convincing manner)... Just keep in mind that the whole thing would be quite difficult to translate into English. I suspect that adequate fluency in the French language and a fair understanding of Parisian slang--as well as a thorough knowledge of French popular culture--are prerequisites in order to enjoy this unpretentious little movie to the full.