Well that depends, when are you planning on going?
If it is during chirstmas week, make reservations.
If not, then yes for the most part you can wing it, and still be able to have sit down meals in the resturants.
However, if you are planning on dinning at the blue bayou, or carthay circle, I would recomend reservations, at least for the BB, as that one does tend to book up. Or any of the character breakfasts, or the WOC dinner package.
Again, it depends on when you are going.