One thing that the URL lets me do is fast access to all pendingThat use case is already covered by the link at the top of the email: "View this message online".
I believe that link used to be below the quoted message, where the others are, but it was #suggested that it be moved to the top for convenience. On the theory that if you'd rather deal with the message on site you don't need to scroll through it in the email message.
On my Android phone I use that rather than reply. Not because I care about the extra Sent message but because I like the web interface better than the email interface on my phone.
On my desktop I generally switch to a pinned tab in my browser to review pending messages, and simply treat the email notice as a reminder to go check.