Well i dunno why... but for my guess the engine acoustics have a
part in giving a car that "powerful" image. V8s have very grunty
kind of accoustics, popularized by the hot rods in the US way back
in the middle of the 20th century. V12s gives a nice high-revving
kind of feelling. I can't describe a V10 engine accoustic cos... i
dunno how to describe 
so maybe that's not the appealing part haha... just
a wild guess.