Personally I side with Tateru on this one. This debate has raged for as long as I have been in SL. I all comes down to exactly what is SL, who are the residents and why do they stay.
I believe no matter who you are, and how you live your second life, you stay here because Second Life fulfills some need that you can not fill in real life. The physically disabled dance. The shy and the withdrawn interact. The emotionally troubled find solace. The ambitious find opportunities. The creative create. But, and it is a big but, it takes a newbie time to identify his or her needs and find their place in SL society. Rare indeed is the person who comes knowing their destination. Time and again I have seen people who think they want to play in combat sims discover satisfaction as a content creator; or those who are going to make their fortune as a land baron end up finding a contentment they did not know they needed in a D/s relationship.
People who’s real lives are fulfilling and without perceived limitation do not last long in SL. To that extent Second Life is a niche market and always will be. The best anyone can do is persuade newcomers to spend the time to find out if Second Life is for them.