...and it needs to stay.
LFR gave us:
1. chance to join raid whenever we want
2. chance to leave raid whenever we want w/o seeking approval from guild RL
3. chance to go afk for bio/walk dog/eat w/o seeking approval
4. chance to see the content while doing 1 and 2
5. chance to get some loot to advance character gear wise
6. chance to advance character skill wise (for those who want it)
7. chance to not having to fill guild apps looking like RL job apps and feeling like looser while doing it
8. chance to not have voice comm and not listen to stupid/immature chat going on
9. chance to be meter-*hore just cause you feel like it
10. chance to not been asked for achivement/gs/ilvl for raid which drop lesser ilvl than you are required to have
11. chance to have real life back having time for all friends, family, wife, gf, kids, grass-cutting, going to pub, having a hobby...
12. chance to play Wow less to have time for no.11
Pretty good reasons to me. Feel free to add more.