Time to roll for initiative! Sure, you could keep your dice in the plastic container they came in. Or you could go for something that actually feels like an item your in-game character could own.
When you grab into your backpack to get out your dice and your fingers hit that smooth leather, you instantly get the feeling that you're sitting in a medieval inn and are reaching for your pouch to take out your precious gold coins. Did you not spend hours selecting the right colour and material of dice for your character? Are these dice not worth their weight in gold just the same?