I've had the opportunity (misfortune) to use quite a few different systems over the years - BlackBoard, Sakai, McGraw-Hill Connect, WebAssign... and out of all of those I have only found these services to be useful for two things -
1) Submitting papers online - it is much more convenient (and environmentally friendly?) to submit our essays and papers online, just uploading them to Sakai or Dropbox or whatever than it is to print them out and hand them in.
2) This is where technology has actually been really useful - Math Homework - my college assigns all of our math homework through WebAssign. Basically, we sign in, and it gives all of us students similar problems, but with somewhat randomized constants (e.g. I see "integrate this from 0 to 3", but for my friend it will be "integrate this from 0 to 4" etc). The nice thing is the way the system grades our answers - it actually evaluates our answers to see if they are mathematically equal to the desired answer (within certain limits, for example if it asks me to integrate something, I can't just put in the integral, I actually have to do the work) so, basically if the answer is Pi/3, it will also accept 3Pi/9, etc.
Using WebAssign for our math homework is by far the best use of technology I have ever seen in a classroom. It will let us try up to 5 times to answer each problem correctly, and we get instant feedback on our answers.
Using technology in the classroom only goes so far, in my opinion BlackBoard added nothing at all to my high school english class, it just meant that I had one more site to check for homework ever night. I didn't even like doing our chemistry homework online - the system was far to picky, if you have to draw a diagram of a molecule and your diagram wasn't oriented the same as the system was expecting it would just mark it wrong, even if the molecule was accurately drawn.
I don't blame professors at all for ignoring a lot of the technology they have at their disposal, many times it only makes life more difficult for them and their students, and moving the class homework online very rarely adds anything to the class. However, when technology is used correctly, it can make a HUGE difference - online work is the reason I passed Algebra 101 in community college.