I rather agree, so long as it doesn't turn out to clutter up the table too much. The '/msg me' option is only good at the time the replies happen. You could just look at the thread, but you only get the reply count if your node was the top node of the thread, plus that's doing things one at a time.
in reply to Show reply count in "Nodes you wrote"?
If the goal is to go back and look at your nodes with no replies, adding this column would indeed be nice. You may even decide to update or reply to your own nodes when you find that your OP turned out to be some FAQ or you figured out a solution on your own.
Of course, one shouldn't expect replies to nodes other than thread-starters, so the reader will have to look for the absence of /^Re[\^\d:]/ in the subject line.