I wonder why the Orion Multi-Purpose Crew Vehicle will only allow ocean landings while the Soyuz spacecraft is capable of landing on land?
Also, what mode of landings does the Chinese space program envision for its spacecraft?
Back in the early days of space flight, the Soviets did not have large expanses of warm water available to them, where there is no fear of 'enemies'. Unlike the US with large coastlines on the Atlantic and Pacific Oceans.
Thus necessity was the mother of invention, and the Soviets needed to land on land. They use parachutes, and solid rockets that fire in the last second or three of flight to slow down the final touchdown.
The US on the other hand, used water to cushion the landing as it is much simpler. Hard for a water surface to fail. (I suppose if it froze, that might count).
On the other hand, as noted by several commenters, the Russians, launching mostly over land, needed to handle an abort that ended on land, and the Americans launching mostly over water needed to handle an abort that ended on water. On the gripping hand, eventually in both those cases, an abort could end on the other type of surface.
It is easier to NOT rely on something always working, with no time for backups to take over. So the US took the easy way out historically.
Orion is not very 'revolutionary' and is not really doing anything new. So it is no surprise they did not try to change the landing mode.
Of course the Commercial manned space providers are not planning on water landings, since they must do something revolutionary to make an affordable business case. (NASA does not have to deal with petty things like that).
So SNC with Dream Chaser is a runway lander. Boeing with CST-100 is a land lander, but with the final blow cushioned by air bags. (Which means throwing away the heat shield every landing). SpaceX planned initially on powered landings for Dragon V2 but that plan has changed over time back to water landings.
I am pretty sure the Chinese using a Soyuz clone, land on solids cushioning the last bit, on land.
Geoffc gives all the main information, but it's worth adding that precision in such a landing is low. If you splashdown in an ocean, you have no risk of hitting something you wouldn't want to, like a tree, or a sharp boulder, or a car.
Also, a landing Soyuz normally hits the surface and then rolls for a bit, rather than hitting, sinking, and then bobbing back up, which i would imagine is less nauseating and less of a shock.