It's a great step for the University. If a student comes to the lecture, they will learn something whether they intend to or not. This should, theoretically, raise the grades of the students in the classroom, which will raise the grades in the University as a whole.
Think of this in a case where you're in a lecture and the professor puts his notes online. Students see this and decide they don't need to go because they can simply read the notes themselves and learn it on their own. This doesn't necessarily mean the prof is bad, it just means that the students are a bit lazy. Even if they do end up reading the notes (which is rare), they're still missing out on critical notes, hints the prof may give, and emphasis on certain topics. Even asking or hearing other students questions. When I was a student, I was in a class that was full and our professor posted his quizzes online, making it so you just had to look up the answers on the internet or take the quiz with a student that did attend class. In the end, I was one of 5 students out of 60. That class had a very low class average.
It's true that students could be in the class that are disruptive, but having mandatory attendance doesn't restrict the prof from kicking those disruptive students out and taking away their attendance for that day. I certainly wouldn't hesitate to remove extremely disruptive students. And if they're there but don't care about the topic, they shouldn't be in the class anyway, or should at least understand that you need to take the class and should make an effort to understand it.
I don't have a study to show you about this, but if you look at it from the view where it's good and think about it, it's pretty obvious there are reasons for it. Schools without the mandatory policy look at schools that have it and see that there's benefit for it, which is why that put it in themselves. No school would put a mandatory policy in without checking into its effectiveness, especially if it's the main step to making their school better.