I'm all for having comments if it's carefully designed.
Data Explorer is open source and a patch that adds this kind of feature would be more than welcome.
I am totally swamped with bringing more awesome to the Stack engine at the moment, so I have not had too much time in the last few weeks to work on SEDE.
So to answer your question, there are plenty of plans I would love comments, graphs even possibly something like "gist" that you can embed into your site and code contributions would be more than welcome. What is lacking though is time :)