The expendable design makes more sense, and is in line with the philosophy of the Empire military! I had always found the hyperdrive ring on the Jedi fighter kinda stupid: if it gets destroyed after you leave it behind, you become stranded and have to call for help…
I though it just stayed in orbit or in deep space until the fighter returned? Or is that an EU thing maybe? I’m pretty sure I’ve seen/read that the fighters can return and use them again.
Perhaps they were saying that enemy forces could destroy the rings, not that they are single-use.
As for the concept, I think it’s neat to be able to shed excess weight for increased maneuverability, something that Jedi pilots would probably prefer. I also think there are plenty of ways these rings would be beneficial in a military engagement, especially if the fighters were part of a strike force containing larger ships. The rings could be left adrift around the larger vessels or even remotely operated in order to draw enemy fire. Any hit on the disposable rings would be one less hit on the large vessel.
Even on its own, a hyperspace ring would probably be difficult to track down by enemy forces if left in high orbit or deep space because of its low/nonexistent power signature - they’d basically have to be searching for what amounts to random debris, which is again more time with their attention drawn away from the real Jedi threat.