On the other hand, the lowest deck is usually much closer to the dining room!
This could be a big plus in some peoples book! As stated, the lowest deck also has the least "motion of the ocean". If you're prone to motion sickness, this too could be a big plus, especially if your cabin is also mid ship. The lowest deck is usually very quiet as well, unless it's very near the bow, or the stern.
The elevators are also empty when they get to the lowest deck, so you won't have the problem of the doors opening, and the elevator full, like often happens when you're on the decks which are about in the middle.
I wouldn't worry about the cabin on deck one or two. They'll work just fine.