Speaker-oriented (or "stance") adverbial hopefully has been taking abuse pretty steadily for 30 or more years (see MWDEUThat's followed by some excellent, concise insight about very, which everybody who's been told to never use that word should read as well.). Linguists are mostly just baffled by this disparagement; see the discussion in the American Heritage Book of English Usage, where it's noted that "hopefully seems to have taken on a life of its own as a shibboleth." But the word fits right into long-standing patterns of the language -- cf. frankly in "Frankly, this soup stinks" and surprisingly in "Surprisingly, this soup is delicious" -- and it provides a way of expressing the speaker's attitude towards a proposition which is both (a) brief and (b) subordinate: "I hope that S", "I have a hope that S", "It is to be hoped that S", and the like are wordier, and have the hoping expressed in a main clause (as the apparent main assertion), while what writers want is to assert the proposition provisionally, adding a modifier expressing their attitude towards it. So speaker-oriented hopefully is a GOOD thing, and it's no surprise that it's spread so fast.
For more on hopefully and ambiguity, see this and this.
Oh, it's a good day when it begins with sane information about style and usage!