I remember a few years ago, LAX->TPE roundtrip would cost $3500 thru their hot eFares. Now the tickets are regularly $4500+, and normally $4800 for the more popular night flights.
What gives? Does joining star alliance mean they can get away charging higher prices?

I am guessing you are not an economist

The whole point of improving their product is to improve demand so they can charge more, right?