It seems to me that powered speakers are actually getting cheaper than passive+amp, which makes sense because the amp becomes cheaper to produce, stock, and ship. If you compare the JBL PRX525 to the MRX525 (which perform similarly) the price difference is not very large and you're not buying an outboard amp. However, as I keep saying, you can't take that amp and use it with a different speaker.
I think powered speakers will eventually become the norm. The low cost of DSPs to make them very flat and protect the drivers from damage will keep getting better. You won't be able to get that without a good outboard processor, configured correctly for the speakers, and an appropriate amp gain/sensitivity setting. Beyond that, powered speakers that once contained an amp and a passive cross-over network are fast becoming dinosaurs, with multi-channel amps and digital cross-overs taking over the powered speaker market.
I still want the passive + amp flexibility until the sophisticated features I mention above are available and cheap enough that it makes sense for me. But, one day soon, I will have to quit defending passive boxes and jump on the wagon with you guys.