dude. you can jump to dodge too, and you retain full air control during a jump unlike in TF2. i'm not getting this "1-dimensional strafe to dodge bullshit" that makes curved trajectories suddenly undesirable.
revolver bullets have a curved trajectory, and they're not that hard to dodge at mid-long range. if anything, the speed of the projectile plays the biggest role. a straight flare versus a curved flare is irrelevant because the flare itself isn't as fast as a revolver bullet, nor should it be.
anytime someone is on the ground and are able to jump (also depending on their position), they always have three options to dodge, and in two axes: move left/right, jump, or don't jump. dodging flares is the same as dodging any other projectile. the slower the projectile is (flare), the easier it is for that player to react and dodge. curved trajectories doesn't change this at all.