As explained to me by Dave Thurston, well known flying boat designer, tailwheel is the preferred arrangement for a flying boat amphibian which is to be beached. If you are beaching a tricycle flying boat you will contact the ramp nosewheel first. If there is any wind or current, the aircraft will pivot around the nosewheel before the mains contact. You'll by pointed up the floatplane ramp at an angle, and possibly unable to taxi out (and probably not back in either). The taildragger flying boat will contact both main wheels at once, straighten you out, and you're on your way.
When I park the flying boat in the water, I put the main wheels down, run them up onto the bottom, and it holds the plane in place very well, while protecting the bottom from damage or wear.
It was mentioned about crosswind capability. Consider the distance between the fin and the contact point of the main wheels. Tail draggers are a greater fin to mains distance than the same aircraft as a tricycle. That means more leverage for the crosswind to pivot the aircraft around the mains. It would take more rudder to overcome this. I have certainly landed tricycle Cessnas in crosswinds I would never attempt in a taildragger of the similar Cessna, but it is very skill based, so others could fairly differ on that.