You make walls to shut others out.
But it's you who get trapped in the end .
I have met only very few extroverts in my life. Those amazing creatures who cry when they're sad , laugh their asses off when they're amused. Who throw tantrums when they are pissed.
In all honesty, they are less confusing. They aren't a mystery. You know exactly what to say to them and when to say  it.
But also they are super ANNOYING.
Those people who unleash their feelings as they wish are disastrous. To the point you wish if you could punch them. They are same as babies, demanding to be listened. They think the world spin around them. They think they are the center of the universe. When they don't get the attention they need they act up. Cry , kick around, argue, sulk .
And they should not be left in their own devices.
They are unpredictable.
We have that person inside of us . Everyone.
He is the one who initiates our feelings first. One who reacts first.
But we keep him caged .
Keep him chained, keep his actions thoroughly restricted.
That's how society works, it's not a bad thing. We all have to co exist, 7 billion of us. We have to fit in some how. Like pieces of a mega puzzle. Each piece is unique but it has a way to connect. It's necessary for the picture to be completed . Whether it likes or not.
So altogether, bottling up a bit of stormy emotions  isn't bad. It's called "patience " . Keeping that spoiled brat on a leash. That's how we socialize.

But......

You should know the limit. When to open the gates , when to remove the leash, when to act up, not to restrict.
Otherwise that person inside you alters.
Either he gets totally dysfunctional. Numb to everything.  Or he gets obsessed with just one feeling. React only with that 24/7. To everything that happens.

Or worst....

He rebels.
He turns in to another voice. Another force . And tries to destroy it's restrictions. Break down the walls that traps it . Break the chains. It destroys who you are. And destroy everything else.
That's how a demon is made.
Emotions that weren't expressed don't die. They are buried and comes to life again.... in uglier ways .