It wasn't changed due to the rapid nature of the fork. It probably will be changed in the future.

BTW, the person who claimed the hive.dao account has already stated it was done to reserve for the community and it can be used for the Hive proposal system if desired.

Despite that it is the Hive development fund, the account is still steem.dao as it is a special account hard-coded into the blockchain. Perhaps it will be changed in the future (although someone has already claimed the hive.dao account name) but it's probably not a high priority.