Should you keep copies of your logs? Absolutely! I made the mistake of purging my files early on and after realizing all the informational wealth buried in there, I started backing up those files as if they were critical to the game. The bottom line is that the logs contain more than just where you have been. Everything you do from ship upgrades to combat to financial transactions to mission progress are in the logs.
Many of the third party tools such as EDDiscovery, EDSM rely upon your logs in order to provide you with historical information not provided online.
Just for starters. Try uploading one or more of your logs into EDSM. Then go to your account tab and look at some of the information that is available. If none of that info is useful or interesting to you, then no, you probably don't need to save your logs.
The Galactic Positioning System of Elite: Dangerous at your service.
www.edsm.net
Check out some YouTube videos on the subject of tools.
https://www.youtube.com/results?search_query=elite+dangerous+tools
Also check out the utils section here:
http://edcodex.info/?m=tools&cat=3 The one hint I would give is that if you do find a utility you love, save the install files somewhere you can get to it. I found that many of the more exotic utilities disappear after the author loses interest.
I might recommend this one for starters by Exigeous. He mentions EDSM, EDDiscovery and a couple of others that leverage the journal files.
Source: https://www.youtube.com/watch?v=kYIko-pGbl8&ab_channel=EDTutorialsbyExigeous
