Yes, I think it's a pretty bad reason, yet it seems to be the very reason most people of all races, classes, genders and orientations do it. I could certainly think of many far worse reasons to have kids, but I personally have a hard time coming up with good reasons to have kids at all.
I had this discussion with my mother just yesterday, actually, about how people who want kids ought to think long and hard about WHY they want kids, and to recollect every horrible thing that's gone wrong in their lifetimes (to them and to the world at large) and really seriously consider if it's worth potentially putting a child through all of that and more just to "give you something to do" or to have "a little you" around. Life's not always dark and horrible, I know, but it's something people never seem to consider when deciding to have a kid
All I know is I have a lot of problems with anxiety and depression, and I wouldn't wish that on anyone, even if it means "living on" through procreation, which is a BS concept to me anyway.
I think, if you are truly prepared for a child, you should have one if you want one. I just don't think most people really ever are prepared when it comes to considering all the negative existential implications of bringing a child into the world.
EDIT: I'd also like to add, if you have to have a kid, it's really a good idea to consider adoption. That way you at least don't have to live with the guilt of bringing someone into the world, only about screwing them up with bad parenting. ;D