IQM format is superrior to other formats supported by DP. It's native exporter for Blender for once, which exports directly to IQM - no mess with intermediate formats. IQM can be used for static meshes with no bones, for static meshes with bones, and ofc for animated skeletal meshes. IQM supports vertex alpha which allows texture blending on animated models. The format is optimize for faster loading and for better performance. Why would I use something else?!
DPM requires to export into SMD first (or MD5, which currently has no Linux util to parse into DPM and exporters for Blender are broken), then convert. Plus I'd have to mess with text files to specify anims, fps, looping, etc.
And coding animation is easy - self.frame = 1 plays entire animation

Very useful for animated map props.