Again, who cares? They have the audio from Wembley on multitracks so they can release THAT audio for the live album.
Yeah, cause if you compare Montreal '81 to Wembley '86 you'll hear a huge difference in Freddie's voice. The same happens if you compare Michael's voice from LA '89 to his voice from Seoul '96.
With that said, you'll hear a minimal (almost non existent) difference if you compare Freddie's voice from Montreal '81 to his voice from Tokyo '82, just like how it's a minimal difference with Michael's Wembley '88 and LA '89.
So I don't really understand your logic...
You say the quality is bad for Wembley. Well, that's too bad cuz it might the the best quality Wembley concert you'll be getting anytime soon. But if you'd be offered LA '89 you'd complain about his voice in that concert (which is still great, but nontheless). Why? You can have the audio from Wembley (which you seem to love) on the Live album, and the video from LA '89 on the DVD (which is better than the Wembley quality).
So what's the argument then?