"Ah, but here's the thing with homework!" Ms. Future Teacher says as she steps onto her soapbox...
I agree that homework is definitely a pain in the ass. And I agree that teachers give out WAY too much every night. However, there has to be some sort of homework going to these kids on a regular basis.
I'm now a student teacher and I've been given this schpiel about how important each step of the learning process is. You have to test a student's prior knowledge before teaching to gauge their content knowledge level and adjust your lesson accordingly. Then, you have to deliver the information in the most effective way you can. After the bell rings, they need to be able to go home and recall what they learned, and perhaps even personalize it, to store the information in long-term memory.
If you send kids home without homework every night, they will come in the next day remembering nothing; we're talking tabula raza. But if you give it every night, they're going to hate it and never give it a second thought after they blast through it. Creating a happy medium and providing homework 2-3 times a week that allows them to connect to the material is key.
For example, I just gave a lesson on Friday about Louis XIV. They came in to the room listening and responding to 17th century music, then they saw a short Power Point with lots of pictures and guiding questions about Louis' reign. Then for homework they are responsible for choosing one from 3 possible connection activities that make them use what they have learned and personalize it (they got to choose from a sensory figure, postcard, or letter). My supervisor who observed commended me on the lesson and agreed that the assignment would definitely help them remember the information, because they've made it their own.
So I promise, homework can and does have a valuable purpose if done correctly. Now, are most teachers doing it correctly? That's another story.