What most people overlook is that the 146 was built for airports that have obstacles on climb out or short strips and so on (true 'regional' airports such as LCY etc). Four engines are so that it can maintain the performance required or better after an engine failure. That is also the reason it is a bit slow and has a low ceiling. You can't have everything and the compromise with the 146 is on the short strip side of things rather than than the fast and high side of things. The maintenance required on 4 instead of 2 engines is just another case of the compromise between performance and costs. Also, it is quieter. Jet noise is a lot higher if the jet eflux is faster (ie the difference between the still air and the jet is high). If you can slow the air down (4 slow streams of air as opposed to 2 high speed streams), you will have a much quieter aircraft that can operate into city type airports with less complaints.
The job it is designed for it does very well - quite a few pilots complain about certain aspects of the 146, but I hear it is very easy to fly and it certainly does the job it was designed for well.
J-R