Sorry, but every arrow shot out of a bow has bend in it, unless you're shooting rebar, even then (probably a little bend depending on the length). Weight at the front of a flexible shaft will accelerate slower than the rear causing bend.
As for the straightness issue, the difference between a .001 and a .006 is literally the width of a human hair over the entire length of an arrow. That equates to less than .02% grade over the length of the arrow. I'd bet a paycheck that nobody here can build an arrow precise enough that either the nock, fletchings, insert or broadhead are off less than that. I know everybody spins their arrows, but I doubt anybody could detect that kind of difference either. Arrow straightness is about selling arrows for all the reasons mentioned above: we spend tons of money on everything else, we better have the best, you never know, etc., etc.