Why do Japanese live-action adaptations appear to have extremely similar artistic direction to their manga/anime source material? It is possible that my premise is extremely flawed, but I have noticed in recent times that there are quite a few live-action adaptations of Japanese anime or manga that look very similar in visual style to their source material. For example, I recently saw a trailer for the Japanese film Parasyte, which is based on a manga. Many of the scenes from the trailer look identical to parts of the manga, and the appearance of the parasites is identical to the original artwork. I also saw the movie trailer for Attack on Titan and the titans in the film look identical to those in the manga and anime. There are quite a few other examples that I've encountered that I cannot list right now. 

In Hollywood, even when animated material is adapted to live-action, usually the artistic direction is quite distinct between the two. Some of Marvel's latest superhero movies borrow a lot from their comic book material, but even then their visual style is quite distinct from the "comic book" look. The film adaptation of Watchmen was extremely similar in both plot and artistic direction to the graphic novel and it was critically panned for this, which leads me to believe that it is somehow deemed unacceptable to do this for Western graphic novels.

Is there a reason why the live-action adaptations of manga are so close in appearance/artistic direction? Or is it just my limited experience?
I probably have not watched enough live-action drama TV series and film adaptions of manga to verify whether or not they do, for the most part, bear extremely similar artistic direction to their manga/anime source material; however, this is not surprising if it is indeed the case.

The reason it is not surprising is that Japanese culture values sticking with tradition and establishing traditions. This is why their traditional arts such as tea ceremony, ikebana, kimono manufacture, and sumi-e painting are not interested in "innovation" but rather pride themselves in remaining unchanged in technique and materials/tools.

Most Japanese companies follow a tradition of doing things procedurally as they have been done up until now; they are generally averse to streamlining, experimenting, and risk-taking (this is the launching point for the plot of the TV drama 「フリーター、家を買う。」 [Part-Time Worker Buys a House]: Take Seiji quits his job after only 3 months because his company will not allow any newbies to suggest improvements to make operations more efficient).

The Takarazuka Revue all-female theatre company has adapted a number of manga titles into stage musicals. Once they create choreography for the musical, it becomes tradition and every single performance of the same show must be danced using the exact same choreography as the first production. A prime example is Versailles no Bara, which has, arguably, very out-dated, over-dramatic and poorly-choreography dances and battle scenes from the very first production in 1974, but despite adapting the manga into a variety of perspectives (i.e. Oscar and Andre version, Oscar version, Andre version, Fersen and Marie Antoinette version, Girodelle version, Alain version, Bernard version, etc.), no dance moves can be revised for the revivals (when the company stages the show again for a new run with a new cast).

In this vein, for live-action adaptions of manga to attempt to replicate with live actors the scenes and "camera angles" that the mangaka made and which the fans already love matches Japanese tradition. Another way to think of it is loyalty. Japan has a solid history of respect for doujinshi and other doujin works, so if you want to take someone else's work and adapt it liberally, you are free to do that (some professional mangaka do draw doujinshi of manga by others); if you want to make an official adaption, it makes sense to be true to it and meet fan expectations and hopes.

Another aspect of Japanese culture is the concept of accuracy, meticulousness, and painstaking attention to fine details. Although Japan does not invent as many products as some other countries do, they have a tendency to take someone else's invention and greatly improve upon it in small details (for example, the automobile) and have thus gained a global reputation for quality technology. This penchant for aiming for precision and correctness would also lend itself to depicting a beloved work as respectfully and exactly as possible.