"Ultimate Superman" wasn't a direct sequel to "Smallville." Otherwise it would've been set in the future. Remember, the Clark Kent in that show lives in the PRESENT day. Yet "Ultimate Superman" was also set in the present. It just had elements of the show.
I know it was suppose to be like a mixture of smallville, ultimate Marvel and Stan Lee's Just Imagine and now we got All Star DC. Not that I'm complaning but I thought Ultimate DC would make a good universe.