Some will say the trailer is more stable with a lower center of gravity...
I have drop and straight utility trailers... there is a noticeable deck height difference.
I use the drop axle most of the time, the lower deck height let me use the tailgate as a ramp for moving things like refrigerators or I can back up to a city curb and drive my riding mower right in... no ramps required.
Now, my home made dump trailer has a straight axle and it benefits my dump design by being higher up, there is more room or travel for dumping when I raise the bed
Drop axles are generally forged as far as the drop goes because it has to be made stronger... I have seen one or two drop axles with the spindle bent from too much weight of going over a pothole loaded.