Hi Ingo,
We considered allowing sensor_msgs/FluidPressure (originally called Pressure) to be fulfill this role, but ultimately Fluid Pressure is used much differently than force pressure.
Here's the review:
There's definitely enough robots using this kind of sensor to potentially justify adding a message and we have some existing messages to use as a baseline for what should go into common_msgs (we like to see a history of proven uses).
If you want to propose and lead a review for the message, you can follow the instructions here:
Ultimately it will depend if the reviewers can agree that the ultimate message will work cleanly across different implementations of hardware.
- Chad