Kassadin is lacking in his kit

What made Kassadin strong pre season 4 is the fact that the magic damage on his activated W stacked on towers and inhibitors and the fact that his E had a 3 second slow. At this point, Kassadin is considered a weak champion due to his lack of CC. Without Silence in his Q or a longer duration slow for his E, he can only be used as a burst assassin or anti-mage, which he is still lacking in since his MR per level was removed before Season 4 and his W/Q/E burst has been lowered ever since Lich Bane's scaling was lowered from 75% to 50. I appreciate the fact that he is still mobile, but he is lacking everywhere else, thus he is considered a weakling.

I highly recommend that his E receives a buff to the duration of the slow (perhaps 55% slow for 3 seconds at max level) or else he will continue to be looked down upon. All that Kassadin has going for him is that he can be highly mobile (so long as he has CDR and mana) but what else does he have? He is not able to get everything he needs when his base damage on his Q and E have been lowered in Season 3/4 patches and he NEEDS to be forced to build lots of AP in order to do damage.

Perhaps it would be better to rework his scaling and base damage so that, let's say his Q does 260 dmg at rank 5, but his scaling is 55% AP or 60% AP. Or how about removing the base damage from his ultimate and increasing the mana scaling on it so that he can do more damage with it mid/late game. This makes it so that he can be more flexible in his build.

I may be asking for a lot, but without anymore cc then a 1 second slow in his kit, Kassadin is REALLY needing a buff to his E and or Q.