yeh, data from the third party tools can be exported and integrated back into your wordpress, but I still fail to see reason to use them. Why should I make the effort to integrate them, what is my ROI? engagement can't be a goal by itself.
For my personal blog I don't care about the number of comments, I care about their quality - how interesting or educating they are for me. For an adsense powered site I care only about ad click. IMO the only people that care about engagement are those still stuck at 2000 and its "eye balls" models.

The fact that techcruch replaced FB comments with livefyre suggests to me that even facebook can't deliver a meaningful engagement, and if they can't why should anyone think that disqus or any of the other can?

And the ROI is important for any change you do in the site. If it is a non profit site then you just do things you have time for, but if you need to pay someone to enhance your comments then you should see a way to earn money out of it, and the end result should not be more difficult to maintain then the current one, and all the things that were discussed here require more time devoted to moderation and spam fighting (or clearing false positives), so how do you justify to yourself this additional commitment?