I think they've officially used up their free three-film Ticket To Ride after "Coraline". They still have a cult with the animation fans for "Come see our latest because we made it by hand!", but what they make is starting to have less and less breakout appeal.
My feelings on Paranorman are well known by this point, there is no love for The Boxtrolls, and Kubo looks even more like the legacy of the Samurai Jack Fanboy Generation twenty years later than "Secret of the Kells" did.
Not sure about all that, but as for me I am not a fan of any of their other films. This is the first one I've liked and it is partly because it is different from the others. But after three similar films viewers may have thought this would be more of the same.
I'm loving what I've seen of Kubo (no confusion in the title for me...?) and can't wait to see it, though I only really liked Coraline before. ParaNorman was a drag and Boxtrolls had good elements but a weak story. Kubo just looks epic!
Still not knowing too much about the story, I wasn't really thinking that his guitar-thingy was part of the title, or was just assuming that at some point it would lose a string or he'd have to replace the strings and only have two but find he could play just as well with two as with three, etc. If that's not the case then, yeah, it would be odd to call it Two Strings.