To me, it's not so much Picard. It's Patrick Stewart. We absolutely do not need more of him, just like we do not need more of William Shatner playing Kirk. But other actors playing those characters, in earlier time periods, would be just fine, if not better. We have almost no knowledge of his time as captain of the Stargazer during the Lost Era. And since one era in Star Trek is really no different from any other era, I'd rather watch a show about young Picard on the Stargazer than a show about 7 of 9 on the Enterprise-G.
My problem with Picard is that he's the prototypical Trek unquestioned "good guy" (the guy who needs a mirror version of himself in order to have anything resembling an edge).
Seven, OTOH, is a far more interesting character. This woman was evil incarnate for eighteen years. Every day, she's fighting the temptation to go back to the Borg.
This woman has a monster inside of her. She has one of the most complicated psyches in all of Trek.
I'd like to see how she interacts with the young crew on the E-G.