Not officially, there was a leak on the oficial MK website. A bunch of audio files were found of Shao Kahn and Character slogans and intros. One of em was Stryker, others were Goro, Sindel, Quan Chi, Smoke, Noob Saibot, Human Sektor (weird I know), Ermac, etc. Even heard audio clips of Shao Kahn saying "Brutality" and "Test Your Might". I got em here saved on my computer now.
Not "Officially Announced". We just found out he's in by alternative means .
It's fairly simple to understand once you realize that most people are idiots. They hate things because it is "popular" and try to rationalize it afterward.
When MK3 was released, most of Stryker's haters were those who didn't like his appearance. At the time, their position was understandable as Stryker was the odd man out. He was the "normal" guy in a sea of the supernatural.
Fast-forward almost two decades.
Now, more games are made with a realistic slant than a fantasy one. Our entertainment culture has shifted toward the darker, grittier, and more realistic aspects of fiction. Look at the Borne films. Look at Christopher Nolan's work. Look at the Daniel Craig Bond movies.
Turns out that Stryker was just two decades ahead of his time.
Anyone under the age of 24 who is very vocal in their hatred of Stryker is a complete moron. They have little to no capacity to form their own opinions and instead listen to what the popular consensus says.
To not care for or have no opinion of him is understandable. To hate him is mindlessness.