These interfaces aren't broken gratuitously. They change to accommodate new features or to allow for better code reuse within the kernel. In the long term it's only a significant maintenance burden compared to letting the driver stagnate and never gain new functionality or optimization after initial release. Manufacturers might prefer that development model since it helps sell more chips of the next generation, but it's really not what should be used as the baseline.

You only have to fix your driver if it's outside the kernel tree. Drivers in the tree get fixed by whoever's making the breaking change (which is why it's important that certain hackers be able to read and understand all related drivers).