Hi, Carolin4,
I was also about to start a thread about the same topic until I found yours.
The version of Magician that you were using was probably 4.9.7 before you reinstalled Windows. The new version of Magician (5.0) does not include the "OS Optimization" features and that is an expected behavior rather than a bug, I believe.
According to some researches I performed on the same subject, apparently (just apparently) the OS Optimizations suggested by Samsung Magician 4.x in Windows 10 were questionable in some aspects even for Microsoft engineers.
Please, check this link:
https://msdn.microsoft.com/windows/hardware/commercialize/manufacture/desktop/hard-drives-and-partitions
The most important part is:
Solid-state drives
--------------------------------------------
A solid-state drive (SSD) is a hard drive that uses solid-state memory to store persistent data. An SSD must have a minimum of 16 gigabytes (GB) of space to install Windows. For more information about drive space and RAM considerations, see Compact OS, single-sourcing, and image optimization.
Note It's no longer necessary to run the Windows System Assessment Tests (WinSAT) on SSD drives. Windows now detects SSD drives and will tune itself accordingly.
So I am assuming that Samsung removed this "OS Optimization" in the new version of Magician intentionally, knowing that Windows 10 no longer needs it (according to that link).
One last thing:
As I had the same concern, I ran Performance Benchmarks on Magician 4.x where my system was tuned for "Maximum Performance" and on Magician 5 (with the lacking OS Optimizations features) and I got the same results so I am starting to believe that, in fact, we no don't need to change anything regarding "OS Optimizations".
Now I am also doing the same research about overprovisioning as that is another thing that is missing on Magician 5.
The fact that this can be easy done via PowerShell or Disk Manager is not the case for me but if it's worth it or not.
I found many people defending the idea that over provisioning is the way to go for maximized lifespan, including this link:
http://www.kingston.com/us/ssd/overprovisioning
My only concern is that the articles are from 2010, 2013 and as they are gone in Magician, I am also revisiting this topic.
I hope I have helped.