For some time now, we've been hard at work rebuilding our Seller Admin interface from scratch in DHTML (HTML+CSS+JS), as our current, Flash-based Admin has become too complex and crufty to modify readily without breaking it in unexpected ways. Thus, most major new features and functionality have been "backed up behind the dam" of launching a new, modifiable and extensible Admin that will allow us to add new settings and controls for our clientele to manage such features.
Between that project, providing tech support to our clientele, and maintaining and improving our existing system to keep up with our growth and improve performance, we've got our hands quite full, so we simply don't have the spare resources to provide more direct, hands-on assistance with custom development needs, for which (as mentioned above) we refer clients to our Developer Directory listing numerous independent developers available for hire (many of whom have done rather impressive things with frontend/client-side customization).
Most other, fuller-featured ecommerce systems out there are "licensed" solutions, meaning they provide a copy of their software to install and operate on the merchant's own server, making it possible to modify and extend just your own copy of the software if/as needed. These solutions can be rather technically challenging to set up, which is a daunting task for business proprietors to undertake on their own, and there's so many of these solutions already competing with each other, all doing much of the same things, that we decided not to compete with them at all, and instead focus on an under-served niche.
E-junkie is deliberately positioned as a very simple, basic ecommerce solution to meet most simple, basic ecommerce needs, designed to be easy for DIY'er business proprietors of limited technical inclination to implement in their sites without much trouble or technical hassles. As such, we are a "hosted" solution (sometimes called "software as a service" or SaaS), which is centrally-managed on our servers and shared in common among all merchants who subscribe to use our service in their sites. This removes most of the technical challenges for merchants to start selling online, though it also involves some inherent tradeoffs, such as the inability to significantly modify how our service works for just one merchant without applying the same modification to all other merchants.
Thus, we need to consider any potential modification in terms of being a general feature/functionality enhancement accessible to all our merchants, which cannot break or significantly alter our service's existing behavior as-deployed on thousands of sites; if any settings or controls are necessary for individual merchants to manage their use of the new functionality, that needs be added to our Seller Admin for everyone, which as a practical matter can only be done in the new Admin we're currently still building.
Sometimes a merchant's business grows to the point where E-junkie is no longer the best tool for their particular job, so although we'd be sad to see them go, we'd rather see them move on to another solution that better meets their actual needs. If you're driving a VW bug that suited your basic transportation needs for a while, but you've since come to really need a delivery van, you'd do better to just get that van, rather than try to make your VW more van-like.