Yall are both wrong. You don't need these files to jailbreak, there will alway be a way to JB.
These files are needed to restore your phone from a jailbreak. It's possible that you wont be able to restore your phone in future apple firmwares without these files. These files are sent to apple's servers when you restore, if your ibes and ibss files are different apple will know, and wont allow a restore.
This was posted yesterday from apple:
http://support.apple.com/kb/HT3743
Inability to apply future software updates: Some unauthorized modifications have caused damage to the iPhone OS that is not repairable. This can result in the hacked iPhone or iPod touch becoming permanently inoperable when a future Apple-supplied iPhone OS update is installed.