If people were more considerate about others, then possibly no. The reason excuses exist is because we feel we need to have one in order to keep our job, or status with another individual. I mean, I suppose it depends on what kind of excuses you are talking about? The made up kind or the real kind. If you are making up excuses for something that is basically lying. If you have something that really came up and you are using as an excuse then I don't see an issue. I see that more as apologizing that a situation came up.
I think the question would more so be, do they help us survive? I don't really think so. I think what you are trying to refer to is more like are giving reasons to someone necessary for survival as apposed to is apologizing necessary to survival (as per the definition of excuse) I think it helps us with interpersonal relationships to a certain point, but will only help so far till people stop having faith in you. I believe they are more used to make ourselves and sometimes others feel more comfortable about something.
-Purn
