They're certainly the goals. The clearer object names (like namespaces I suppose) are the most obvious benefit. I haven't explored them a lot yet but have read some articles. One I was reading the other day - whilst not directly related to schemas - http://www.sommarskog.se/grantperm.html#ownerschema, had some info on how schemas are different from the old user+schema in SQL 2000 and earlier. The article talks about security quite a bit - schemas play a small role there from memory (you can assign permissions for users/roles to schemas, etc)