Since "Father" admitted he could feel (clearly), what makes you think his loyal comrade didn't either? I mean, it was Brandt's job to know what Preston was "thinking."
Hey there, Johnny Boy, I hope you fry!

but dude!! they cut his FACE off!!!!! I almost cried at that part!!! To ruin such a masterpiece lol

My thoughts exactly with regards to his repeated smirking. I wouldn't say he ruined the movie, but his character kinda threw me off when compared to the stoicism of Preston I kept wondering "why does he keep SMILING??", in addition to him "he's the one that's feeling!!" when being carried out of the office kinda ironic for him to be shouting that. (And Beans one angry outburst seemed strange too.)
enough with your dumb ass posting cracker

He was supposed to not be on the drugs in the first place, so he could better understand the resistance and see people who could feel and arrest them.
Thats why he was ambitious, rather arrogant, smiled a lot and emotional.

Yup and he did seem quite angry when they carried him off too.
PCL

I don't recall that either.
PCL

When exactly was it revealed he was getting high?? I must have missed that part.

The beginning explained that it didn't eliminate emotions completely but the dizzying highs and the abysmal lows. If the drug was capable of removing emotions completely, they wouldn't need to bother to rate things EC10 and burn them.
These are some quotes from the movie explaining this:
Libria, I congratulate you. At last peace reigns in the heart of man. At last war is but a word whose meaning fades from our understanding. At last, we are whole. Librians, there is a disease in the heart of man. Its symptom is hate. Its symptom is anger. Its symptom is rage. Its symptom is war. The disease is human emotion. But Libria, I congratulate you, for there is a cure for this disease.
At the cost of the dizzying highs of human emotion, we have suppressed its abysmal lows. And you, as a society, have embraced this cure: Prozium.
Now we are at peace with ourselves and human kind is one. War is gone. Hate, a memory. We are our own conscience now, and it is this conscience that guides us to rate EC-10, for emotional content, all those things that might tempt us to feel, again, and destroy them. Librians, you have won. Against all odds, and your own natures. You, have, survived.
Prozium - The great nepenthe. Opiate of our masses. Glue of our great society. Salve and salvation, it has delivered us from pathos, from sorrow, the deepest chasms of melancholy and hate.
With it, we anesthetize grief, annihilate jealousy, obliterate rage. Those sister impulses towards joy, love, and elation are anesthetized in stride, we accept as fair sacrifice.
For we embrace Prozium in its unifying fullness and all that it has done to make us great.
But this one negates the whole thing (maybe because shoddy writing) and is in line with what OP is saying:
intrinsically, humans, as creatures of the Earth were drawn inherently always back to one thing war. And thus we seek to correct not the symptom but the disease itself.
We have sought to shrug off individuality, replacing it with conformity. Replacing it with sameness with unity, allowing each man, woman, and child in this great society to lead identical lives.

The beginning explained that it didn't eliminate emotions completely but the dizzying highs and the abysmal lows. If the drug was capable of removing emotions completely, they wouldn't need to bother to rate things EC10 and burn them.
Some people are naturally more capable of hiding emotions than others. Those that couldn't were just normal citizens. Those that had some capability were foot soldiers. Those that had near-perfect control of emotions studied to become Tetragramman Clerics.

LOL!
"I am the ultimate badass, you do not wanna *beep* wit me!"- Hudson in Aliens.

The drugs in the film don't stop people from feeling. That would be impossible. The drugs mute the feelings.
Taye's character, it was revealed in the end, wasn't taking the drugs in the way they were proscribed. He was using them to get high. Which is why he was bouncing from calm to extremely manic. And he never got into trouble for it because he was Father's right hand man.