This has absolutely nothing to do with LFR and instead has to do with MMOs becoming playable for solo players by changing the EverQuest-era mechanic where progression was not possible without a group. You can thank Vanilla WoW and its sisters for that. (And you should, it opened the genre to a much wider audience that has since learned to appreciate cooperative play too)
I would never, ever have gotten into the detailed aspects of MMOs if I hadn't started with WoW and its gentle "Hey, you can level too!" design. Even though I'm way past that now, there's thousands of newcomers who aren't, and we should be supporting and encouraging their motivation to stay in any given persistent or cooperative world.