I'm quite -1/0/+1 on this topic. I would be happier if there was some sort of global consensus in the symfony code, but it seems to depend on who wrote it - i.e. it seems there is no standard policy on when to include or not to include documentation for properties.

+1 for adding doc blocks on properties where it makes sense to the developer.
-1 for introducing comments that are IDE biased.
+0 for making property documentation mandatory.