Basically she's dead now.
Why is riot giving Ezreal special attention by securing his AP alternate build but not Katarina's AD build?
The base damage on Bouncing Blade and Sinister Steel were nerfed, the bonus movement speed from Sinister steel and her base movement speed was reduced by 5 and the damage reduction on Shunpo and duration of damage reduction were reduced.

Why cant Katarina be viable or usable as an AD Bruiser?
Why cant she have Bonus AD Scaling on Bouncing Blade or Shunpo? Bouncing Blade is pretty much useless to AD Kat past the laning phase and Shunpo only gets used for its mobility now since the damage reduction and the duration of the damage reduction were reduced.

Riot i beg you, let us play her AD without feeling like we are a hinderance to our team!!!

Bait:
Irelia
Nerf
Buff
Darius
OP
Ezreal
Morello
Volty
Guinsoo
FeralPony
Coronach
Xypherous

...Because she's an assassin?

Edit: She's a AP/hybrid assassin. AD was never really good, just something to troll with when you were bored. Sustained damage from AA isn't a necessity for a champion that refreshes skills on enemy deaths. It would be overpowered and you would just see people stacking Bloodthirsters and grabbing a Trinity Force to wreck.

so? Ezreal is an ADC, why should he get to viably build AP Mid?

Because if they made all of his attacks physical damage, he would be way too OP as an ADC. So Riot would much rather give him two possible builds to seperate his strengths.

Ezreal was originally AP mid. Katarina was originally AP mid. If you want a 'fairness clause' on why Ezreal can build AD but Katarina can't, you can't have it. Ezreal's AP ratios were nerfed, the heal on his W removed, and he was forced bottom to not be considered a troll pick.

I said it in my post, but I'll reword it.

Trinity Force used to be ridiculously overpowered. In order to make hybrids viable, Riot gave them this extremely powerful item (a good joke was the guy who did the champion spotlights, Phreak, would build a Trinity Force on 9/10 champions without even realizing it). As a result, you had nerfs across the board to hybrid characters. Ezreal, Kayle, Katarina, and Jax were all nerfed substantially as a result of Trinity Force (and their specific kits, as well). Trinity Force, as we all know, was nerfed eventually. The hybrids kept their nerfs, keeping Ezreal bottom and Katarina mid forever.

Now, you could argue that since Trinity Force is balanced now, buffing the hybrid characters seem plausible, but we've seen a rise in people realizing the high base damages of hybrid characters makes them a good target for HP stacking. This is a balance issue that buffing AD (talking about Katarina here) would do nothing but cause problems for.

Furthermore, as I stated in my original post, I can almost guarentee you would see Katarina build 2-3 Bloodthirsters and a Trinity Force/Iceborn Gauntlet. This would just be stupid and I don't want to see it happen.

when did ap ezreal become a viable anything? x_x seriously I just consider it a free win

Since when do people build Mana items on manaless champs? ie trinity force on Kat...

Oh, because it totally doesn't give AP. AD, HP, a proc that slows enemies, and a proc that deals 150% of the person's AD as bonus damage.

Sheen used to be a core on every assassin in the game, regardless of whether they had mana or not.