I think three films is a good idea. LOTR takes a lot of words to depict events whereas the Hobbit is much more concise, in my opinion. Factoring in all the 'behind the scenes' bits with the Necromancer and whatnot I think three films will give Peter Jackson the opportunity to do the Hobbit justice. Having said hat I think two could have sufficed just as well but I can't say I object to someone milking a cash cow if they provide a good experience for the audience. Which they certainly did with the LOTR films.
Except for the godawful siege of Minas Tirith and Battle of the Black Gate. Because charging blindly into hte fronts of giant elephants and then allowing your entire force to be surrounded just makes so much sense militarily.