Yes, but, (1) I'm interested in the breakdown of not only my posts, but some posts of other members, and (2) the reactions are often spread over time and don't appear as one count in the notification.
Seeing who voted positively has two advantages: (1) members often post a one-line comment just to let know that they up-voted some post; this would be not needed, (2) as an extreme example, if JohnPBailey has upvoted my post, I would check what is wrong about it.
So, the data are there. It is only a matter of displaying some of them.