I fly Algiers to Bamako, daily with a 737-600 (120 seats) with competition with another 736 on two days of the week. The route is only 1500nm, yet I am making like 32K a day!
(which is low for one route, but it is short and I have other routes after it).
Now, the max demand that I have ever seen represnted on the graphics is 95 on a Friday. That route has demand of >100, yet I make money off of it. I will fly a 737-600 on a route with only 60-75 people, if its longer than 1500nm, because I will still be able to make money off of it, so I disagree, the 737 is not to big. Remeber, you may get LF's in the 50-70s% but its the yields that matter.