Of course we could name many other reasons, like business, etc ...
I know #minchizu was one of the answer for google+ communities, but this system is in Japanese language only, is in beta test in Japan, and only allow to add and view photos from the post (not the post itself or videos, etc ...), and needs tricks when posting that are not good incentives for posting in these maps.
We created a G+ community and we added this option in our community. as an example, see photo of the map layer of our community below, or the direct link to the map here: http://goo.gl/LZ2A1t, with the link to associated G+ community here to see how we are managing the complexity of this option: http://goo.gl/SZv58O). People from the community and other communities are very interested for the reason I cited previously, but the process is so painful and constrained to photos that most people simply abandoned. Don't misinterpret, they really want this option. It is simply not friendly enough currently.
A better and simpler solution IMO would be to give the option to add a georeference info straight from the post (after or before adding a video or a photo or link). You can see that google type of GPS info in G+ for android (see here: http://goo.gl/aOfNuK). Then if you share your post publicly, the post will be embedded automatically at the right GPS location in a public google map layer. Similarly, if the post is shared in a community, the post will be automatically embedded at the right GPS location in the map layer associated uniquely to this community.
Is it in your plan? What do you think?