System restore has saved many PC's from needing a complete reinstall.
I've done some testing, theres NO real reason to turn it off. It doesn't slow anything down.
Sometimes when it all turns to sh1t, no fix will repair the problem.
Reinstalling a PC complete can be a PITA sometimes - esp when data is not backed up and be honest how many people "really" have images of their systems
Not that many, only the ones who know. The average user wouldn't even know how to do an image.
Theres been countless times I have run system restore on customers PC's to at least get the PC back to a working state.
So turning it off is stupid. What would you rather do - spend less than 5 minutes and have a working system, or spend days putting it all back. As for the amount of space it uses -

If a persons HDD is that full they need a few more MB of space - get a bigger drive.
Edited: Just did a check, System restore is using a whopping 3% of my 250 GB drive, 8.1GB , with the Max available being 9.3GB 4% "whippy de do " and still have 191GB free space.
To see how much - open a Command Prompt and run as administrator, type in
vssadmin list shadowstorage
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