Even if the idea is to separate out those features that are unique to WordPress.com to the New Dash, let me add my voice to say that the new iteration of my activity on WordPress.com is a far cry from the old "Comments I've Made."
It's not about the comment I made, but those comments that came before or, more importantly, after it. If you can't display those in the activity stream, then you've missed the point.
And I'm not interested having all my activity mashed up into one stream. Keeping "Posts I like" and "Comments I've made" separate was a much more efficient way for me to deal with the information.
Also, no interest in signing up for "comment notification" for every post I comment on here at WordPress.com. I get enough email each day from WordPress.com as it is, thank you.