Pockets are one of the greatest inventions in clothing history, so why are they sewn shut when you purchase a new suit? Isn’t the point to, you know, hold stuff?
The reason is actually pretty simple: It’s aesthetic. When people try on suits, they stretch them out, especially when they put their hands in the pockets. The more people that try them, the more dilapidated the suit starts to look.
Manufacturers sew the pockets shut to keep the suit looking fresh. They are usually sewn shut with a single thread, so after you buy a suit you can just snip and pull, and you should be good to go.
But remember, some pockets are purely for decoration, so you might end up with a small hole in your jacket or pants if you cut those…so better check before you start cutting away. Now get out there and dress to impress!