Because this is a problem if you don't notice you are betting bitcoins and your strategy is used for litecoins.

Example being bot crashes you reload it and you won't notice now you are using bitcoins.

Thanks for your suggestion, Like I explained on discord, the difficulty to add this depends on the level of memory you want the bot to have. Either way, it is outside of the scope that I intend to do on v3 of DiceBot. I would rather spend the development time to work on DiceBot v4, which will most definitely remember the currency you were using.