Welcome to the board.
There's been a long history of filmmakers trying to tackle DT. From Wikipedia:
"Initially, in 2007
J. J. Abrams was connected to a film adaptation
[20] but later revealed he had removed himself from involvement in the project.
[21]On September 8, 2010, an official announcement was made that the series would be brought to both the big and the small screens via a trilogy of feature films and two seasons of a television series to bridge gaps between the films.
[22] According to a press release from Universal Pictures from October 29, 2010, the first
Dark Tower film would open on May 17, 2013.
[23] On July 19, 2011, Universal pulled its support from the production of the
Dark Tower films and television series. According to reports, the studio was unable to come to terms with producer
Ron Howard.
[24] Despite this, Stephen King remains confident Howard will see the project through with another studio, and Howard confirmed the adaptation is still on track, noting that
HBO will now carry the television series portion of the project.
[4][25] On March 13, 2012 it was reported that
Warner Bros. is now interested in making at least the first film, and would be in prime position to green-light the TV element through its sister company,
HBO.
Russell Crowe, tipped to play
Roland Deschain, is reportedly still on board. Reports indicated that filming may have commenced as early as the first quarter of 2013.
[6] However, Warner eventually passed on the film.
[26] Later, on April 10, 2015, it was reported that
Sony Pictures and
MRC will be going ahead with the first film in the series alongside a television series, using a reworked script by
Akiva Goldsman, who worked on the initial 2010 proposal, and
Jeff Pinkner.
[27] On June 2, 2015,
Nikolaj Arcel was hired by the studio to direct the film.
[28]"
I'm afraid I can't share your opinion that "most" of the movies that have been made are horrible. There is no doubt that some adaptations are clinkers. But there have been a large number of films that at the very least are competent and in some cases superb. Some of the best adaptations in my opinion are (in no particular order):
The Mist
Dolores Claiborne
Stand by Me
Misery
Green Mile
Shawshank
Creepshow (not an adaptation, but still)
Christine
Carrie
Storm of the Century
While I understand why you suggest Eastwood or Ford for the role of Roland, I can't imagine either being up to the physical demands of the role. Eastwood is 85, and even a three-film project such as you propose would take him to 90. Plus, he hasn't touched Western material for nearly 23 years (Unforgiven), and that film has been widely seen as his valedictory speech to the genre. Ford is 72 and is already committed to a new Indiana Jones film and a new Blade Runner film, which will likely mean he's unavailable until 2017, at which point he'd be 74. That would take him to 77 or 78 by the end of a production cycle for a three-film DT series.