So I have to go into a complete explanation. Okay. Explanation time.
Innate Passive grants him high survivability, and the shield lasts forever so there's no counterplay to it.
Q, on top of the insanely long ranged grab, comes with a free 1 second stun afterwards, which can then be followed by a 1 second knockup, which is then followed by a .5 second silence. This is nearly a 3 full seconds of "completely unable to flash away or react in any capacity."
W is an 8 second 32% MS steroid. That's all it could be and it'd be ludicrous. People always complain about dashes when they talk about mobility creep, but I see all these old champions with long lasting, highly powerful MS steroids, and I'd much rather chase a Yasuo or a Riven over a Blitz any day of the week. Oh, and did I mention that at 40% CDR it's an 8 second MS boost with a 9 second cooldown?
Ult has basically no cooldown and, most aggitatingly, accidentally steals CS from your laning partner with the random damage. The worthless, unreliable, random damage.
So yeah. His scalings aren't the reason he's a giant pain in the ass, and changing them to 80% or 60% or even 0% wouldn't fix anything other than punishing people who want to do something more interesting with Blitz than sit bot lane and be a big, boring, non-interactive threat. He has a kit designed around punishing someone for being out of position while simultaneously having a kit devoted to keeping him from being punished for being out of position.