pioneers do it because they only have one wire... it's blue/white... and is shorter than the rest of the wires... jvc's have 1 blue/white wire... sony's... alpines... and almost every other radio out there have a blue **antenna** and blue/white **remote**... my avicn1 is the only pioneer i've seen lately that has a seperate power antenna wire... that's one thing i didn't like about my 8600...
back on topic... i'm sure no one told you to connect your amp turn on to your constant wire... if they did they told you to put a switch on it or didn't know what they were talking about... you could have connected it to the red **ignition** wire in the harness... then your amp would shut off when the car is off...