The improvements aren't necessary but they aren't unnecessary either IMO. The way I see is that it's just different flourishes and accents but the song remains the same. Burtt used to say that because a lot of the mix was actually done "live", each time they did a pass it was its own performance, and that's sort of the attitude I take towards the mono vs stereo. It's like when you see a band perform live, each concert you go to the songs will be technically different than the last time and with little improvs and modifications and even some mistakes, and some you like and others you miss from last time. If I had my pick I'd go with the stereo mix but I have the strong suspicion that it is purely because that's the only version I knew until about 4 years ago, so it's weird to me when stormtroopers have slightly different voices and there's sound effects where there weren't any before. Also, the recording quality of the mono version is obviously not as good as modern official remasters of the higher-fidelity stereo, so I think it creates an unfair advantage for the stereo mix as it is aesthetically more pleasing to the ear.