An Assassin's mobility or mobility related skill should not deal that much damage at all
Assassins should deal a lot of damage really fast and should typically be mobile, but their mobility move doesn't need to be the one that is the easiest to use while also being the most damaging by far since its more reliable.
Assassins should have to decide between Mobility or Damage, safety or Kill. LB, Akali, Fizz deal so much fucking damage with their mobility moves that you pretty much cannot react and they are so reliable and safe that it doesnt matter if you are over extended in the first place.
yet this is in the game:
85/125/165/205/245(+60% AP) AoE and can be double cast with R
100/175/250(+50% AP) Single target
Q
100% Total AD + Sheen + 10/40/70/100/130(+60% AP) Single target
E
70/120/170/220/270(+75% AP)
Yet,
mobility move deals no damage
Yet,
mobility move deals low damage that he doesn't scale with in the slightest
Yet,
mobility move only deals 60/85/110/135/160(+40% AP) to a single target
Yet,
mobility move deals no damage
Yet,
mobility move takes aiming, timing and actual brain function unlike LB's W even though it deals high damage