The sort of customer profile accounts you describe are typical of full-featured ecommerce software packages that would get installed on your own server and control every step of the shopping experience, from start to finish including checkout itself, entirely on your own site.
E-junkie is a centrally-managed service shared in common for all of our sellers, and since we depend on third-party payment processors such as PayPal to handle checkout, all cart orders are anonymous to our system until after the buyer has already completed checkout, so we have no way to save or apply customer profiles before that point; typically, buyers would maintain a profile with the payment processor(s) they use, such as their own PayPal or Google Checkout account.
Having us manage the ecommerce software for you on our servers spares you the hassles of installing and managing all that on your own, but one of the tradeoffs for this ease-of-use is that our solution has no practical way to implement customer profiles from our end.
