If they do both brands will have terrible divisions. I can't imagine trying to watch a tag team division with 3 teams.
Or watching SmackDown's women's division with what Becky, Nattie and Naomi?
I think that's the whole point though to Build up talent to try and establish them
The Tag Team scene has been dominated by the New Day for the last year, so now Smackdown has their own Tag Division
The Usos - former Tag Champs
American Alpha - up and comers, looking to make a name for themselves
Vaudevillains - came up at the same time as Enzo and Cass, same time the Club came in, same time New Day are still dominating, this is there chance to establish themselves on the main roster.
The Ascension - they've been languishing for so long, this might be a time to give them a bit of edge in a feud, come out and make themselves actually look like a threat rather than jobbing to one of the above mentioned teams that dominated.
Breeze and Fandango - they'll either be the jobber team to the above 4, or maybe this establishes them? at least is consistent Tv opportunity that has nothing to do with comedy with RTruth and Goldust
a 6th option: Ryder and Mojo Rawley - I thought it was strange that they brought Rawley up until I saw he was on the same brand as Ryder. I can see Ryder getting beaten at Battleground by Rusev, then Rusev attacks after the match, Rawley comes out to back him off, and then these two join the tag division.
6 Teams, outside of the Usos, all looking for a chance to establish themselves.
As far as the women goes, not that I really care for watching them myself, you can see why having a Smackdown title would be worthwhile, obviously the only three established ones at the moment are Becky, Natalya, Naomi - I think Bayley will be at Battleground on Sunday to be Sashas tag partner, and in the process she will somehow end up on Smackdown. Not exactly sure how, but that's another story.
These are just my opinions anyway, not saying that its a good or bad plan, just that it is an option that could potentially be explored.