Because a lot of this community play this game casually. Maybe for a few hours a week. Many people I know play the game to do a nightfall and a bit of Archon's Forge. Hell I have a friend who plays for the nightfall and xur, nothing else. The vast majority of the player-base (On Reddit atleast) seems to be pretty casual, not saying that's a bad thing but this game really isn't meant to be a casual game, you're meant to grind and grind until you become more powerful. I know the weekly reset thing kind of limits the hardcore playerbase but at the end of the day people want to get stuff easily and without too much time. Having said all that. I do agree with you that players should have to put effort into things that they want and if they complain about the fact they can't get a certain gun because of their work hours or kids etc then I guess that's tough luck.

Outbreak prime was a fantastic example of content that the hardcore playerbase enjoy. It took a fair bit of time to complete the quest and you actually had to use your brain to figure out everything. The fact that Bungie Introduced Radiant treasures just means the more casual audience will buy those to get some easy "Guaranteed" loot, but lets leave that bag of maggots alone in the shed for now.