Why must we have middle names?

So I've been racking my brain thinking of names and I've come to a conclusion. 
If it's a boy I think I'd like name him Isaiah. But I cannot think of a middle name. Help??!
Isaiah (insert middle name) Daniels. 
I just love the name Isaiah so much. 
However if it's a girl I definitely want to name her 
Aubree Marie Daniels. 
My husband was like saying to just not use a middle name but I really want to have full names.