Granted. I do think problems in the domain of number theory are a bit different. I don't know of any quickly-explainable
consequences to Fermat's Last Theorem, and in my first comment I was really thinking about consequences. With Fermat's Last Theorem, to my knowledge, the original problem is itself pretty arbitrary, so I'm not surprised to find its solution and proof to be complicated despite the simplicity of the problem statement.
Also, I'll preemptively mention that Gödel showed us that any formal problem is a problem in number theory. That said, a problem like P =? NP would almost surely be incomprehensible if expressed as an isomorphic problem in number theory. So my original point, clarified and rephrased, is that I would expect (or desire) the proof of a problem to be as intuitive as the statement of the problem combined with its consequences in the domain the problem is stated.