It must also has be taken into account that driving has become annoying to the point that many people from suburbs don't come anymore to Paris for shopping, theatres, exhibitions, ... and many living inside or nearby are really annoyed by the public transports which are dirty, not on time, too crowded, beggars every few minutes, ... so biking is like a forced solution that helps with some things but isn't always a choice of preference. It's easier to see this in the winter, which is not cold/wet enough in Paris to make cycling difficult, but there are clearly much less cyclists then.
You describe Paris as if it's a shopping/entertainment center for the suburbs. It also looks like you're implying that Paris needs the economic activity generated by the suburbs. For that I would investigate what a suburb is by definition.
In the 70s-90s, it was! A lot of shops and movie theatres have closed in some areas like Champs-Elysées, Montparnasse, Saint-Germain, ... where people used to come by car from suburbs on the week-ends because they could, because it was practical, because they could park.
Places for shopping and entertainment have been created in the suburbs since then, which is a win for the suburbs but not for Paris which has become depressing.
