I don't see why it's an inherently bad idea. Obviously it could only make NPCs easier or just less likely to attack, so there would be no point using it outside Solo mode. And obviously the actions of players on lower difficulties should have much less of an impact on the background simulation, and maybe rank caps, etc.
But I do not understand the obsession some people have with driving casual players away, the hatred some people seem to hold towards anyone who doesn't have time to spend 12 hours a day honing their dogfighting skills and maybe just wants to fly a spaceship around occasionally without constantly being murdered. Many of the core Elite audience, people who played the original 30 years ago, now have families and demanding jobs. If we're going to game at all, it will be casually. Why are you so obsessed with taking this game away from us?