It seems active or powered speakers are the popular choice when bumping in and out of venues night after night and with digital amplification well and truly tried and tested, the powered speaker is now a whole lot lighter.
So why would you want to use passive speakers??
In small rooms, a good powered mixer and two passive speakers is a very easy and uncomplicated set up. In addition, if I have to do a set up in a high pedestrian area such as a marquee or outdoor function with children running around, I always prefer to just run speaker leads as against running both power and signal cables to each speaker - much safer option! And if there is only one power source, setting up your mixer or amp close to the power is always a good option.
Also, most passive 2-way speakers are 8 ohm and running them in parallel at 4 ohm will draw extra power from your amp so running four 8 ohm speakers on a typical stereo amp (2 a side)will give you excellent coverage without over-driving the system. There always remains a use for passive speakers.