Rename LOB is an expensive operation

[oracle@stormking cdb12102 lob]$ cat rename.lob.seg.sql
@ conn.pdbm.u.sql
set serveroutput on
set verify off

drop table ltbl;
create table ltbl
(
        n number,
        l clob
);
insert into ltbl ( n, l ) values ( 0 , 'A' );
commit;

@ lob.seg.details.sql U LTBL L
alter table U.LTBL move lob(L) store as LSEG;
@ lob.seg.details.sql U LTBL L

quit
[oracle@stormking cdb12102 lob]$ cat lob.seg.details.sql
column segment_name format a30
set linesize 200
set trimspool on

define owner=&&1
define tablename=&&2
define columnname=&&3

select l.segment_name, o.object_id, o.data_object_id, e.block_id
from dba_lobs l
join dba_objects o on o.owner = l.owner and o.object_name = l.segment_name
join dba_extents e on e.owner = o.owner and e.segment_name = l.segment_name
where l.owner = '&&owner'
and l.table_name = '&&tablename'
and l.column_name = '&&columnname'
and o.object_type = 'LOB'
and e.partition_name is null;
[oracle@stormking cdb12102 lob]$ sqlplus /nolog @ rename.lob.seg.sql

SQL*Plus: Release 12.1.0.2.0 Production on Sun Jun 26 11:59:12 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Connected.

Table dropped.


Table created.


1 row created.


Commit complete.


SEGMENT_NAME                    OBJECT_ID DATA_OBJECT_ID   BLOCK_ID
------------------------------ ---------- -------------- ----------
SYS_LOB0000097896C00002$$           97897          97897     740640


Table altered.

The data object id and the block id have changed, meaning that the LOB segment has moved:

SEGMENT_NAME                    OBJECT_ID DATA_OBJECT_ID   BLOCK_ID
------------------------------ ---------- -------------- ----------
LSEG                                97897          97900     740696