Last December Peter Corke and I posted a survey related to URDF and its usage.
We would like to thank everyone that participated in the survey for their detailed responses!
We have analyzed the results, and uploaded a full paper on arXiv.
The main results we found are that people are still interested in URDF being used in the future, but there are number of limitations and challenges that need to be addressed first.
Some of the main challenges are a lack of tools to work with URDF, lack of documentation, and limitations in URDF not supporting parallel linkages or closed-chain systems.