When i bought my ATS65HD some years ago, i was offered a deal on a Kite Skua stay-on case with it, which i took - not really knowing if it needed it or not at that stage.
The Kite case is made from a fairly substantial neoprene, and has been on ever since (other than the yearly run through a cold wash).
The Swaro 65 seems to me to be a fairly robust model and is waterproof, so technically, it probably doesn't need it. However, i have dropped it a couple of times, and feel that the case probably offered some protection. This case doesn't impede any of the functions (zoom, focus) and seems to dry quickly after being soaked. I felt it more substantial than the Swaro one -tighter fitting and more padded.
I kinda wish there was a similar product for the Kowa 883, as i feel a little more vulnerable with the magnesium body. I know of three instances of the scope toppling backwards causing impact to the 'shoulder' of the angled scope, and cracking....
It's really got to be your call on this. It's probably not strictly necessary and many don't use SOCs at all. I just thought that when buying a scope of that price, the 7% or so extra on the price for a bit of extra protection (including sand, dust etc.) was worth the peace of mind.