riddle - WHAT?! AM I BOTHERING YOU?

So often forgotten, unless accidentally used,
How am I so rotten; why am I so often abused?

I'm loud and obnoxious, it's obvious when I'm there,
For I'm not for the cautious, you might use me when you swear.

Take away all restraint, and I'm what you're left with.

What am I?

Answer

You are:

Caps Lock

So often forgotten, unless accidentally used,

How am I so rotten; why am I so often abused?

People often forget they have caps lock on, or accidentally use caps lock, especially when entering passwords

I'm loud and obnoxious, it's obvious when I'm there,

For I'm not for the cautious, you might use me when you swear.

Caps lock enable "loud" capital letters, and it's obvious when people are using it. When people are swearing, I'm sure they use caps lock

Take away all restraint, and I'm what you're left with.

People go wild with caps lock

Additionally

The first letter of each line spells SHIFT, which some people might opt for rather than caps lock

And the title...

Is written with caps lock (or shift, who knows)