I respectfully disagree. Having multiple raid difficulties allows players to choose their gaming experience. I only raid at the mythic level on my Hunters, for example, but my Druid can still enjoy the full raid even though I haven’t played them very much.
LFR also provides a way for people to practice specific boss fights (on new specs, for example) without the hassle of getting into a PuG, dealing with lockouts/skips, or clearing every boss before.