Both GOT and WD suffer when they stray from the cannon. For GOT, the added stuff last year was terrible and added nothing to the story.
Perhaps it's better to see the written version and tv version as two separate entities.
I haven't read GOT or TWD, but in following threads like this one I've found that many people who follow print & film versions for one or both series tend to be pretty crabby when the tv versions do not meet their expectations.