Hi Michael,
I have been in conversations with Nik Kalyani of the core team about this over a year ago. My position is that generic functionality should go into the core. Specific functionality is the domain of the module developer. Tagging and categorization are perfect candidates for core inclusion and Nik aparently has solutions lined up for this. Behind the scenes I still push for this, but core changes take a long time. About third party dependencies: that is very tricky and something I do not support. I hope the solution will come from collaboration with the core team.
In the meantime: please use the keywords field for your tags (semi-colon separated). You can search them. And you can be sure if the core solution does materialize I'll be using this field to migrate to that.
Peter