I just like certain things....for example I added the EDM800 because I think running a helicopter powered by a piston engine on an oil temp gauge, a single CHT and an oil pressure gauge did not give me adequite visability nor tracking of my engine performance. The EDM800 gives me all 6 CHTs, all 6 EGTs, Oil Temp, Oil Pressure, OAT, Volts, MP, hottest cyl, coldest cyl, % HP being used, fuel flow, hours/minutes fuel remaining at present power setting, fuel required to next waypoint, fuel required to destination and more at a glance. Plus it tracks all of this information and logs it every 6 seconds for me to download via a USB port on the front panel for tracking and trending of engine performance. To me that is a lot more valuable than say a single CHT, Oil Pressure and Oil temp gauge!
So I guess the reasons I customized the panel so much with everything is because I like the cool stuff I added and "I" feel that it provides value to "me".