Why? So they can continue to ignore it? It only takes 15 minutes of perusing the posts in here to see that nothing ever changes, Intuit doesn't actually care about innovating or creating the functions that people actually need. Why on Earth can desktop carry over costs from an estimate to a PO and QBO can't? There's no answer that paints Intuit in a positive light. They either can't figure out how to do it or they don't care. 

Let's not even address the fact that you don't convert a PO to an estimate, you convert an estimate to a PO. Ya'll really need to work on your bot algorithms.