Let's face it, in today's world bandwidth consumption, even on mobile devices, isn't really much of a big problem anymore.
Try using it on a GPRS connection and then tell me that. It's less about the bandwidth usage, but more about the bandwidth of the connection you're using it on, and hence the experience using the forums.
Before I moved to university, I had GPRS coverage pretty much everywhere near where I lived, no 3G in sight. Maybe in some countries 3G coverage is much better, but there are still plenty of areas where it's not.
Interesting speed comparison here, between a browser based system and a properly optimised API based application:
As a side note, should a proper web-based API ever be developed (the efforts seen in the programming forum could be used to this effect) I might pick this application up again and make it work with a new API. Either that or I might just open source it, let's see.