Hi,
Regarding the Stripe API ; it requires to create a customer in their platform in order to use the customer ID when creating the charge.
stripe.com/docs/api#create_charge
So, it is not something which can be done easily like that, it requires tests to be sure that nothing will be broken.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.