Thats not entirely true, although I'm on your side as I think its pointless, Intersango's new fee structure does make business sense: it delivers on the goal of reducing spreads. Their thinking is a tighter spread will lead to more customers. For those who unknowingly sign up, the buys will be more expensive then they expect. I think this is stupid, however it has made the exchange favour sellers. If you dont mind using two exchanges, you can use this to your advantage for your trading activities.
I think you're being imprecise with your word choices "favor sellers". It actually favors liquidity makers. They can be buyers or sellers, so long as they do not accept the bid/ask on the other side of the transaction.
I stand corrected. You're right. Intersango favours liquidity makers.