Hi Michael:
It is mainly an issue of cost, these plates are universal where the connectors are the most expensive components. The plates are all standard but have pretty good minimum order requirement. It would also be fairly expensive to tool up such a universal wall plate. There are some terminal cups that you can buy that feature angled connectors. These are used by home speaker builders for both Bookshelf and Tower speakers. We will check into what might be available to add to our current lineup. We can check with our factories.
Good question
TL/3776