Good question... I think sometimes people ttc for all the wrong reasons. But heck, who am I to decide
I am currently ttc because I believe I am in a position to provide for a baby. I love kids and it has always been a life "plan" for me to have a family. I think we are blessed to be able to have the love of family, I am ready for that blessing.
As far as having siblings. My dh is an only child, I come from a family of 5 kids. I love having siblings. I think the family bond between brothers and sisters can be so strong. I would hate to not have that love and connection, therefore, if I am blessed enough to have more than one child, I would be happy to accept the responsibilities that come with it.