Because studying Milton is like studying Kabbalah: it is preferable to do it when you are over 40 and have read and studied everything else there is to read, in every language.
Okay, so I know that's not true, but it's a funny I came up with at Tea and a Real Miltonist told me it was good material.
Milton's a little later than most of the authors I study, and even though I am enraptured by his writing and teach it as often as I can, I just don't quite feel mature enough to write about it. It's not about the Hebrew, Latin and Greek- (sm)all of which I have (boast much, Pamphilia?). It's about the ideas contained therein. Sure, I might reference Milton in my writing now and then, do a reading of a passage, that sort of thing. But a reference does not a Miltonist make.
I think I'll wait to publish anything seriously devoted to Milton till I'm 40. Or after tenure. At this rate, they'll both happen sooner than I'd like to think.