I teach (math) in a Catholic high school, and my 3 kids have/do attend CCD since they are public school kids. I taught CCD for about 10 years... I only stopped a few years ago when my husband rose to a position leadership in a big parish organization. Since someone had to be home with the kids, I scaled back my own volunteering.
Here's what I see as the problem: far too many parents send their kids to CCD and expect those 60 minutes a week to take the place of other religious training. They're too busy to take the kids to mass, or too concerned that the kids won't behave there as toddlers, or have an important soccer conflict, or simply not interested. One of my neighbors-- she has a preschooler-- was disappointed that the local (non-Catholic) nursery school hadn't taught her daughter her prayers. I suggested she start with the Sign of the Cross and Grace before meals.
Many of the kids I taught in 5th or 6th grades had not been to mass since their First Holy Communion. And the odds were decent that the next time they would be in mass after Confirmation would be for a funeral or wedding. Some, like a neighbor, admit that Confirmation is merely a way to get grandma to get off mom and dad's case about a lack of religious background.
As a result:
1. CCD must assume, justifiably in most cases, that the kids know nothing, and start from scratch.
2. There's no time for anything beyond the basics. Homework becomes necessary, because CCD classes are playing catchup from the get go.
3. CCD teachers are volunteers. So there's no way to ensure that your kid's teachers know their stuff, or are good at handling kids of a particular age, or that they have any classroom management skills. But the DREs have their hands tied-- without the volunteers, what are they to do?
4. It's tough spending that extra hour in class after a full day. And it's also tough to teach a lesson that has some umph, but will also be entertaining enough to keep a group of kids engaged. It takes some real prep to come up with a lesson plan that leaves the kids knowing more about their faith than they did when they walked in, while keeping them interested enough to learn it.
I'm not sure what the answers are.