Using an open textbook or other open educational resources can require a lot of time and energy. So why have so many faculty decided to do it? Here are a few reasons:

• Cost Offsets for Students - The cost of textbooks has risen over 1000% since 1977, largely because students are "captive" consumers who have to buy their assigned texts, regardless of the price. Across the country, switching to open textbooks has saved students millions of dollars, and these savings impact other areas of their lives as well.
• Improved Student Satisfaction and Academic Performance - Evidence is mounting that the cost savings of OER use for students is only the beginning of their benefits. Studies on the impact of open textbooks on student satisfaction and outcomes have both found positive results. The Open Education Group compiles studies on the efficacy and perceptions of OERs by faculty and students, many with promising conclusions. 
• Faculty Customization - Unlike traditional educational material, OERs are meant to be changed, remixed, and adapted to fit the needs of the faculty member. If a chapter of an open textbook doesn't fit the learning outcomes of the class or has outdated information, it can simply be removed, rewritten, or replaced with a chapter from another open textbook.
• Student-Centered Pedagogy - Switching to OERs allows the faculty member to involve the students more directly with the content. Students can alter open content, create their own open content, and/or use open content to make something new.
• Lifelong Learning - Rented textbooks and textbook access codes often limit how long students have access to content. Open textbooks are available to students for consultation before and long after their course is over.

There may be other reasons that faculty choose to adopt open educational resources, including an interest in promoting access to education, opportunities for recognition by a larger global community, or an interest in sharing already-created content, among others.