Why get a Combo rather than separate Jointer and Planer/Thicknesser?

I expect I would be needing both a jointer and a planer/Thicknesser but am wondering the advantages of getting separate machines or a combination machine. Looking through the net, I can't see any discussion on the advantages/disadvantages of the different options. I can see some advantages of a combination machine but since I don't own either, I am looking for input. So, here goes and please add:

Combination Jointer and Planer/Thicknesser:
Pro - saves space in the shop
Pro - for the same money, you seem to get a wider jointer than if you buy separately
Con - ???

Separate Jointer and Planer/Thicknesser:
Pro - quick to transition from one tool to the next
Con - ???

Why get a Combo rather than separate Jointer and Planer/Thicknesser?