I agree about the specs, they will never be dead on, but when some are outside a tollerance of 5% it makes you wonder.
On the standardization of woofers, that does not seem relevant. In your view you can use a dvc as a svc speaker. So why make a svc, how can you have a configuration that does not work with a dvc driver if you can use only one coil if need be? A DVC woofer can fit every application a svc could in your perspective.
The good thing about your perspective is once the 1st coil goes on a dvc you can use the other.....lol

. Dont you think the coil that is not powered will be added weight (thet was not designed to be there) and cause the woofer to fail prematurely?