Or is it better to just read a lot, study books on writing, form my own writing groups, and practice and keep submitting, while ignoring the massive pile of rejection letters from magazines?
This is an excellent question, one I went through myself when deciding whether or not to go to a Master’s program. I think that the things you just listed are perhaps ten times more important than the program. That’s not to say that the program is useless, but if you’re willing to do those things, doing an MFA program will add only a little extra value. The added value you get from an MFA program is different perspectives on your work from different types of readers. The disadvantages of an MFA program are–and this has been talked about a lot in the MFA community–that they are very good at developing one type of writer. And someone who writes mainstream Science Fiction and Fantasy is not the type of writer they are good at developing. This means that you’ll have a little bit of a fight on your hands. Some people won’t get your work, some professors won’t like your work, and you will feel pressure to write like everyone else is writing in a lot of these programs, which could be detrimental. On the other hand, you could learn things from these people. I feel that my Master’s program was more useful to me in letting me have extra time to explore my writing without the pressures of having to go find a real job. It also introduced me to some people who became very good friends and writing colleagues over the years.
I think that a good workshop is invaluable. But it has to be a good workshop. I did a Writing Excuses episode or two about what can go wrong. A workshop is basically a big writing group, and the things that a workshop can do are the same sorts of things that a writing group can do which is to offer you reader response on your work, which I think is important. If the professor is really good, it can get you a higher caliber of critique than you would normally get in a lot of writing groups, which is nice. I enjoyed my workshops. The disadvantage is most workshops can’t really dig into a longer piece. If you write novels, across the course of a semester, you’ll maybe submit three chapters instead of the ten or twelve you could get feedback on if you submit every week to a writing group. So there is that disadvantage. Like I said, the workshops at MFA programs can be bad at helping popular fiction be better popular fiction, instead trying to force it down a road which will actually make it less marketable depending on your own perspective and your writing style. There’s nothing wrong with the type of writing that they like to do, it just may not be right for what you want to achieve.