There are several motivations for flipping (or integrating) the classroom. The face-to-face time, which is valuable real-estate, is reserved for more active learning. The integration of technology into learning activities caters to different learning styles, allowing personalised, flexible learning. Students also learn how to learn, preparing them for lifelong learning, both for further study and their future professions. John Bergman explains how in this simple video:

One of the concerns about adopting a ‘flipped’ classroom approach (where face-to-face time is used for application of knowledge that students have supposedly already acquired through independent study) is that students come unprepared to class. There are various strategies you can apply to try and make sure this doesn’t happen.
How to get your students to come to class prepared – Bob and Lynn Gillette (associate professor of economics at the University of Kentucky and former president of Sierra Nevada College respectively) make use of CPAs – Course Preparation Assignments – that are graded pass/fail and an integral part of assessment.
​Ready to Flip: Three Ways to Hold Students Accountable for Pre-Class Work – Once you clarify what you want students to actually DO prior to class, then what? How will you hold them accountable?
3 Articles to Address Student Preparation and Motivation in the Flipped Classroom – Barbi Honeycutt provides some ideas to encourage students arrive prepared, including setting aside a corner for students who haven’t completed the preparation activities and NOT giving a quick ‘catch up’ mini-lecture – otherwise you will be doing it every week!
Flipping the classroom isn’t the answer – let’s scramble it! – Pamela Barnett makes a compelling case for not throwing the baby (direct instruction) out with the bathwater (mind numbingly boring lectures). She discusses how the active learning part of the ‘flip’ does not have to be relegated to the classroom and can (by virtue of technology) begin at home (or wherever!). Similarly, minilectures can still occur in the classroom. I suspect this is how most of us view the flipped practice anyway, but as Pamela points out, words  matter.