I've always wondered what autotrim is good for. I mean, trimming is not that difficult, is it? You do it with your thumb, instinctively, mostly subconsciously.
As far as Airbus FBW is concerned it's not a question of easy or difficult but auto trim is essential design philosophy. It's not even the trim which comes into picture later it's the control which is held in position as commanded by the pilot through an integrater. Then the trim takes over. Airbus is for automated flights.