LOL you used kassadin in that?
Lets see what kassa has....
Bad wave clearing.
Roaming potential ONLY AFTER 6 and even then it is debateable.
Early game presence? Only after 6 and then its mostly used to get away because if you try going in you are ganked.
Some forgiving mana costs if you can W consistantly.
Lols for cc. Hes got a slow and a "if i dont use this, i have no ranged damage, but if i perfectly predict it it can interupt a channel"
What team fight presence? If he gets fed he can kill 1 person before he dies unless he is SUPER fed. At which point an Alistar going full AP could do the same and provide more utility.
He has some poke potential but it puts him at a very great risk of getting cced or ganked or out traded back because of its very short range. (By the way, lux isnt a mobile laner. So saying "can out trade other mobile laners" is not correct). (Oh wait you are biased into thinking only mobile laners are good. Explains a lot that you are thinking narrow mindedly)
Kassadin has to get up close to use any of his power spikes. If vs another champ that excels in close combat fight (talon, Zed, Diana) or vs any longer ranged poking champ (Ziggs, Lux, Ahri) he pretty much is forced to sit there and flop around behind minions and wait for a gank that the jungler does all the work and Kassadin jumps in and Qs and takes the kill.
LOL "makes good use of ignite". Kassadin uses teleport mid or barrier.
Kassadin has no hard cc and only a little soft cc. He cant fight outside of poking them down tk killable levels or getting fed and 1hkoing someone. Hes got a okish high when fed and a VERY low low when he is beat in lane. If he is beat in lane he pretty much is just a running punching bag.
Kassa cant aid in anything really until 6 and is ahead in gold except for saying "hi! Im here! Notice me senpai!" Or as previously mentioned the ally jungler does all the work.
He cant fight anyone he cant 1 combo pretty much.
Kassadin cant fight 3v1. He can barely deal with 1 person in lane let alone 3. 0 wave clear of his that doesnt put him in massive danger of being taken out.
Sure, he can use nimbus or manaflow band. If thats a win condition for mid then nearly every mid caster wins and can never lose to someone like Zed or Talon or Yasuo since they dont use those as effectively (maybe talon with nimbus).
He can only make ADC explode if they are fed and the ADC isnt able to kite them (vayne, Caitlyn if they are good) or out damage them with heals (jinx, draven).
Kassadin is melee.
Kassadin is literally "cucked" by hexdrinker because you instantly cant 1hko them which means you are pretty much dead.
You are trying to judge a fish and a turtle based on how they can climb a tree.