I think the few apps for Maemo are not only because of the low popularity but because how complicated it is to start with developing apps for Maemo. Nokia is on the right way with MADDE and WRT, global QT etc. but before that (and even now) it was (is) really hard to start. Even if you have developed an app for Maemo you have to package it and send it through devel, testing, wait for approval etc. without a good app store. So nearly every application is made by the community and not by companies because the integration between developers, applications (and how to get them on the phone) and the device owner is bad. The whole optifiy problem, SDK not always acting exactly like the device itself, forcing a newbie to install development apps etc. makes the Maemo platform look immature. If Nokia wants to be successful with Maemo in the future Maemo 6 must have got rid of all those things. You can only be successful when the end user is satisfied and currently Maemo 5 is only satisfying for a small group of persons compared to the whole market. Because of the Apple and Android app stores it has become really important to have a lot of (simple) applications with an easy installation.

Just my 2 cents...