Do あなた think I should un-fan all those people on this site who never fanned me back?

Honestly, like あなた said, that's up to you. Personally, I wouldn't but, like, that's because I'm too lazy to do so and don't really see the point. I don't really unfan people unless they persistently bother me.

Frankly I've always seen fanning as less of a friend thing and もっと見る of an, 'I like the content that あなた post/I share the same interests as you' type thing.

It depends on how あなた look at it. If あなた think of becoming someone's ファン as "friending" them, then maybe あなた wouldn't want to remain their ファン if they didn't reciprocate. But others (like myself) ファン people because they like their contributions または agree with some of the コメント they've made, so it doesn't matter if they don't ファン me back または even if they're no longer active here.

I personally wouldn't bother as it would take up time I don't care to use. If あなた feel strongly about removing someone who didn't ファン あなた back then be my guest. It doesn't matter to me in the long run. So I am in a similar ボート as Flicker.

It's up to you. I wouldn't do it as it's a waste of time and energy. I never understood the point または value of adding as a ファン here. It's not like フレンズ get extra access to privacy または something. So, I just ファン people if I have enough respect for them. And if someone adds me first, I usually add them back as an act of formality または common courtesy. The whole add as a ファン thing is nothing but a boost of ego here または sense of security/insecurity. The blocking system is somewhat useless too.