Like everyone else on Earth, I'm thoroughly stoked about the Superman trailer, and one reason that I haven't seen mentioned as much is, obviously casting the role is always going to be mostly about finding a guy with The Look who can also act, The Look is extremely important, but historically it seems like casting directors have focused on build and/or a certain type of facial bone structure, which is all well and good, but casting a guy who's 6'4" is a *fantastic* choice. There's something about that characteristic hunch of a man who's Big But Feels Weird About It that is so, so perfect for Clark. Just seeing him walk down the street a head taller than everyone else but looking like he absolutely Feels Weird About It does so much heavy lifting -- it's both genuinely who Clark is (hello, fellow human beings!) and perfectly lays bare how the secret identity works (your coworker is big and handsome and should by all rights be desirable, but he's still such a loser about it, the loser radiates from his core). It's just a great element of visual storytelling.
Additionally, I have now done some deeper research (Googled "Christopher Reeve height ") and discovered that Christopher Reeve was also 6'4", so that's probably a factor in why it feels so perfect to me. That's just how tall Superman actually is.