To me online alone sucks. That's not R*'s fault. However, online with friends is fantastic. When GTA 3 came out my friends and I would take turns playing, during which we would always dream of being able to split screen- or even better, play online. Here it is. But I am a social person, and refuse to game without at least a buddy.
Playing GTA Online without anyone you know is going to be doing missions with people you don't care about, or worse, getting ran over by people you don't like. I don't see the pay off.
But I am like that with all games. Battlefield is boring to me alone, same with COD. Hell, I thought APB on PC was the greatest thing ever (I still do), but none of my buddy's game on PC. It got boring fast. I just can't do it.
GTA Online. Forcing you to get real life friends since 2013.