Seriously they've done awful at coming up with themes with balance. My guess is they googled stats and said "hey, 50% of the population is night owls/early birds that works" without understanding what it implies if you let people CHOOSE which they prefer. Especially when kids are involved, which, unfortunately, in NoA territory, makes up a good chunk of the player pool (not so in Japan - kids buy 3DS, adults buy WiiU...oh wait, nevermind, nobody bought WiiU... :p)
Though in Splatoon's case I wonder how many of the kids are really playing. WiiU sales aren't exactly lighting charts ablaze, and Christmas was long ago. I haven't seen a lot of Miiverse posts anymore about "they keep putting me against level 50's!" and instead it's a bunch of A&S ranks complaining about the finer points of their teammates competitive failures. A year later, I think only the hardcore are playing to begin with. So child psychology may not be a huge factor this time around.