A、Oracle does not allow replicating files between data centers, so keeping transaction log in database allows for replication.

B、Many transactions in WebLogic are database centric, so keeping log in database makes Two Phase Commit protocol possible.

C、It obviates the need to keep in sync two replication technologies (file and database) between  data centers. The single replication technology is used for frequently changing data.

D、Transaction log in a file system is extremely slow so it cannot be efficiently replicated.