For some teachers, it seems to be their best friend. And I'm the first to admit, that in my first year of teaching it was my best friend too. I was teaching kindergarten /elementary school kids and was clueless as to how to go about this. My school offered no real practical help, nor did the books we used, which filled about 2 out of the 20 hours that I was allotted to teach each class, each month. I had never taken a training class or read any books about teaching ESL. So, I had a lot of class time to fill. I did this by handouts. Coloring, math worksheets, whatever I could find in the teacher's room. The connection to English teaching was quite vague. I'm sure you can extrapolate from this that I was a very ineffective teacher and whatever the kids learned was in spite of me, not because of me.
After 5 years of teaching in Korea, I hope that I do a lot better job at teaching than I did back then. And I'm pretty sure that I do. Do I still use the photocopier? Occasionally...perhaps once for every 4 classes that I have.
World Link,
the main book I teach from has an excellent
Teacher's Resource Book 
with games and activities for the students that are interactive and communicative.
Smart Choice,
the other book I use a lot has an
okay workbook
that I will use once in a while by way of review.
Some of my coworkers seem to make a handout or copy some sort of puzzle or game for every class that they do. I've even seen some of them sitting in the corner reading a book after they've given the papers out. It makes me question their effectiveness as a teacher. It's mostly just laziness that makes teachers resort to the photocopier. It's an instant lesson plan as opposed to thinking and processing how to make the given material interesting, relevant and engaging. It's easier in class too. You can just give the handout, sit back and relax for the rest of the class as opposed to an interactive, communicative lesson where you need to keep the energy up and keep the class moving along and on task. But is it good for the students?
NO! Of course it's not for the following reasons:
1. When you have a handout, you don't really need to process and think and debate and wonder about the language. You just circle whatever answer you think is maybe okay. This is no way contributes to meaningful use of the language.
2. Language is a social thing and learning it happens in dialogue. If you're doing all this paper busywork, then you're not really engaging and learning.
3. The 4 language skills are writing/speaking/listening/reading. I try to do activities that use at least 2, and hopefully 3 or 4 of these skills. Worksheets? They might cover one, if that.
4. It's boring.
So, to sum it all up. Photocopier does not equal toxic in low doses IF the things copied are chosen with care. Used everyday? It's just laziness and I'd question how much learning is actually happening in the class.