ok, all modes have their own sound. its like saying whats up with so many different chords, when you can just play one and itll sound OK. yeh but itll sound better if you use different ones (that was a bad analogy but w/e)... for example, when you listen to pink floyd, they do alot of switching back and forth between, Im, and IV MAJ, and over that, they will just fool around with a dorian mode, (D-D in the key of C)... get the modes off line (mixolidian, dorian, etc) and test em out, to each there own, everyone likes differnt ones. i personally love mixolidian mode i use it all the time when i solo.