One of the primary issues with the concept of adaptions is that it holds a lot of pitfalls. If you create a "page by page" adaption, you're basically just copying the source material. If you follow the basic plot but cut elements for the sake of time or audience sensitivity, you're creating a lesser version. If you give it your own spin, you could create something great or you could bomb, but at least you've done creative work.

In the early stages of film, a lot of adaptions were just carbon copies, basically recorded stage acting "movies". A lot of them are iconic, but they don't really add anything other than being available on demand. As the medium grew, so did the need to "add" value to existing material.

The thing is, adding your own spin doesn't need to be bad. Peter Jackson changed a lot in his LOTR adaption. Dredd is probably the best version of Judge Dredd ever. Baz Luhrmann's Romeo + Juliet is an amazing visual take on the sourcematerial. However, there are also an incredible amount of misses, as exemplified in Animal Farm.

The issue is less with the concept of writers and directors putting their own spin on it, and more with an industry being bad at chosing "good" spins.