FC3/4, RDR and GTA are open world with side missions and lots of stuff to fool around with. TLoU is a masterpiece that is maybe 14-15 hours long at most unless you're playing on the hardest difficulty. I don't expect The Order to be nearly as masterfully made so 10-12 hours will be great.
I agree with this, big open games should have longer completion times because they're not all about the story and keeping you fully immersed in it all the time. You need breaks for exploring and finding other fun things to do. Linear games like the order and TLOU are all about the story and cannot drop the ball at all, which is why they're better if they're shorter.