Why airfares keep rising despite lower oil prices

Supply and demand. I think that if they would just roll the fuel surcharge into the published price people would become more aware and think about using other means of transport where available. Or use budget airlines more.

Now, Wall Street analysts are worried that lower oil prices are causing them to recklessly add new routes

You mean like Virgin cancelling the London-Narita route and replacing it with a London-Detroit route?