Two reasons why CDG has never developed the business traffic of AMS.
One is the flight timings.
AMS allows for flying out in the morning and back in the evenings, even if on different days. This helps keep business costs down, making travel both more practical and keeping rates charged by businesses more competitive.
The second is cultural.
It's a lot easier to work in The Netherlands and Belgium through English.
If you ever travel regularly on the Amsterdam flight, you'll see that there are 20-30 faces that are on the Amsterdam flight every Monday morning. Most work in the Pharmaceutical Consulting and IT Consulting sectors and fly out every week returning on a Thursday or Friday. As we're not known as the greatest polyglots, those opportunities are not as prevalent in France.
The AMS route also seems to get a lot of usage from Kerry Foods. I'm not sure what that's about, but I imagine they must have significant operations in The Netherlands. Thankfully, they don't make so much usage that anyone is laying on a flight to Farranfore!