Quality vs Convenience
"Well if you cannot tell the difference maybe FLAC isn't for you ?"
More seriously it so depends on the circumstances in which music is listened to.
On a car stereo or through earphones on a busy train commute, arguing over the best quality lossy format versus a standard lossless format is probably pointless. Background noises will probably have a noticeable impact on your listening experience, regardless of the quality of the speakers or earphones involved.
As soon as better listening conditions are taken into account, the difference in quality will become more obvious. To what extend will also depend on the musical styles involved, how trained your ears are to the instruments played or how often you've played the songs in the past.
MP3, AAC, OGG VORBIS were always driven by convenience and concerns over size. Now that broadband Internet access is more common and that portable audio devices have bigger/faster storage space, audio quality can become relevant again... for the ones who care.