One thing that really held me back in my graduate hybrid writing/literature program was the fact that I'd barely read any modern literature. I'd guess a lot of literature students are in this boat. You know the drill: you take an "English Literature, 1688-Present" class, and after the three snow days, you only make it to 1875.
Add to this that I'd somewhere picked up the notion that anything new was trash. I don't know how exactly I developed this prejudice, but there were definitely enough subtle hints from people who were intellectually influential to me along these lines that it's not a surprise I picked it up.
Even if you take the stance that everything since the 19th century is garbage, if you want to be a writer now, you have to read modern literature. To have only read those who've come up against the big questions using a different diction than you is just foolishness. If only to avoid repeating what other contemporaries have done in trying to translate the old questions into a modern idiom, you need to be aware of what's happened in the last 100, and especially the last 20 years.
I'm still horribly under-read for a writer. I could read another 100 of the best novels of the past 100 years and still not be very immersed. I have to fix this if I want to go further with writing.
So I simply call the prejudice to your attention, in case it is subtly or not-so-subtly in your mind as well. Like most prejudices, it will do you no good. Of course you have to go back in time to get a foundation in where modern literature comes from. But a foundation does you no good if you don't ever get past the second floor.