The Cessna 206 amphibian had to be landed with the right side wheels extended and the left side retracted due to a hydraulic line failure. The landing surface choice becomes very limited. Ice is the very best, followed by grass (wet if possible). Hard surface runway will wear away a lot of keel. If you land on the water that way, you're going to tumble the aircraft over, and wreck it.
All that said, amphibians still offer the greatest versatility in landing, and for landing gear failures, as long as they are flown with skill and discipline. What other aircraft type could be landed one up and one down main, and perhaps have no damage!