It's all a matter of market saturation. V4 has been around for so long, and so many thousands of characters and products for her have already been been released, that any new V4 product released has to compete with all of that previously released product. By comparison, the number of products that are out there for G3F/V7 is relatively small, so any new product is going to have a lot less competition. As for creating a product that works on both V4 and V7... we've really hit the point where backwards compatibility is getting very difficult to maintain, so not only does it add a huge amount of work to the cost of the product to make two versions, but converting the skins requires the use of third party products that the majority of customers won't own. And even if you do that, it's not like G2F, where it wasn't that hard to remap a V4 skin and clone a V4 morph. Remapping for G3F can be very hit or miss, and requires specialized software or custom geografts. It's kind of like trying to make parts for a Tesla work on your Mom's old VW... yes, it can technically be done, but from a vendor's perspective, will the handful of additional sales you might get really be worth all of the time and effort?