Used to be you could get enormous dimensions of usable timber out of redwood. Like, 16"x16" beams, or larger. I mean, you still can, but there are manufactured products that are cheaper, so it's often riftsawn into standard timber sizes for construction. Redwood's very stable wood for stickframe construction, but Douglas Fir is preferred for mass-produced housing (apartments and tract homes) because it's so much cheaper. Further, long runs of straight grain are suited to applications where the wood will be seen, and tucked inside of walls ain't it. It's used for decking because it requires no treatment, so the cost of labor and chemicals and pressure treating other timbers require is not a cost input for redwood, plus it weathers to a silvery gray many folks find attractive.
And that's about all I can claim to know about redwood. Except that a comparatively microscopic market exists for acoustic guitar tops, and an even more teensie-weensie market exists for electric guitar tops.