There are lots of events that might effect "morale", your squad watches a friendly tank turning into a blazing wreck as the turret lands 50 meters away from them...your MMG goes tits up and the Japanese are yelling Banzai! from two hexes away, and so on. Furthermore, the leader that just surrendered could have been a terrible 90 day wonder, and you actually are glad he surrendered b/c command now falls to your veteran sergeant whom you would follow anywhere...
Surrender is not elimination... because ASL has no Lazarus rule that when the leader escapes from being a prisoner, he is suddenly then deemed un-eliminated, and you can have your LLMC back.
You can look at A26.22 CVP and see that elimination and surrender are two different classes of things otherwise they would not be separated by the "and/or" symbol there in and given different values thereafter.